[Federal Register Volume 62, Number 212 (Monday, November 3, 1997)]
[Proposed Rules]
[Pages 59486-59557]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-28747]
[[Page 59485]]
_______________________________________________________________________
Part III
Environmental Protection Agency
_______________________________________________________________________
40 CFR Parts 141 and 142
National Primary Drinking Water Regulations: Interim Enhanced Surface
Water Treatment Rule Notice of Data Availability; Proposed Rule
Federal Register / Vol. 62, No. 212 / Monday November 3, 1997 /
Proposed Rules
[[Page 59486]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 141 and 142
[WH-FRL-5915-4]
National Primary Drinking Water Regulations: Interim Enhanced
Surface Water Treatment Rule Notice of Data Availability
AGENCY: U.S. Environmental Protection Agency (USEPA).
ACTION: Notice of Data Availability; request for comments; reopening of
comment period.
-----------------------------------------------------------------------
SUMMARY: USEPA proposed in 1994 to amend the Surface Water Treatment
Rule to provide additional protection against disease-causing organisms
(pathogens) in drinking water (59 FR 38832: July 29, 1994). This Notice
of Data Availability summarizes the 1994 proposal; describes new data
and information that the Agency has obtained and analyses that have
been developed since the proposal; provides information concerning
recommendations of the Microbial-Disinfectants/Disinfection Byproducts
(M-DBP) Advisory Committee (chartered in February 1997 under the
Federal Advisory Committee Act) on key issues related to the proposal;
and requests comment on these recommendations as well as on other
regulatory implications that flow from the new data and information.
USEPA solicits comment on all aspects of this Notice and the supporting
record. The Agency also solicits additional data and information that
may be relevant to the issues discussed in the Notice. USEPA is
particularly interested in public comment on the Committee's
recommendations and whether the Agency should reflect these
recommendations in the final rule. In addition, USEPA is hereby
providing notice that the Agency is re-opening the comment period for
the 1994 proposal for 90 days beginning on the date of publication of
today's Notice in the Federal Register. USEPA also requests that any
information, data or views submitted to the Agency since the close of
the comment period on the 1994 proposal that members of the public
would like the Agency to consider as part of the final rule development
process be resubmitted during this current 90-day comment period unless
already in the underlying record in the Docket for this Notice.
The Interim Enhanced Surface Water Treatment Rule (IESWTR) would
apply to surface water systems serving 10,000 or more people. USEPA
intends to promulgate the final rule in November 1998 as required by
the 1996 Amendments to the Safe Drinking Water Act. The Agency plans
subsequently to address surface water systems serving fewer than 10,000
people as part of a ``long-term'' Enhanced Surface Water Treatment Rule
which may also include additional refinements for larger systems.
Key issues related to the IESWTR that are addressed in this Notice
include the establishment of a Maximum Contaminant Level Goal for
Cryptosporidium; removal of Cryptosporidium by filtration; revised
turbidity provisions; disinfection benchmark provisions to assure
continued levels of microbial protection while facilities take the
necessary steps to comply with new disinfection byproduct standards;
sanitary surveys; inclusion of Cryptosporidium in the definition of
ground water under the direct influence of surface water; and inclusion
of Cryptosporidium in the watershed control requirements for unfiltered
public water systems. Other issues that are discussed include
inactivation of Cryptosporidium, viruses and Giardia lamblia; uncovered
finished water reservoirs; cross connection control; and recycling of
filter backwash water and filter-to-waste.
Today's Federal Register also contains a related Notice of Data
Availability for the Stage 1 Disinfectants/Disinfection Byproducts Rule
(DBPR). USEPA proposed this rule at the same time as the IESWTR and
plans to promulgate it along with the IESWTR in November 1998.
DATES: Comments should be postmarked or delivered by hand on or before
February 3, 1998. Comments must be received or post-marked by midnight
February 3, 1998.
ADDRESSES: Send written comments to IESWTR NODA Docket Clerk, Water
Docket (MC-4101); U.S. Environmental Protection Agency; 401 M Street,
SW; Washington, DC 20460. Please submit an original and three copies of
your comments and enclosures (including references). If you wish to
hand-deliver your comments, please call the Docket between 9:00 a.m.
and 4 p.m., Monday through Friday, excluding legal holidays, to obtain
the room number for the Docket. Comments may be submitted
electronically to ow-docket@epamail.epa.gov.
FOR FURTHER INFORMATION, CONTACT: The Safe Drinking Water Hotline,
Telephone (800) 426-4791. The Safe Drinking Water Hotline is open
Monday through Friday, excluding Federal holidays, from 9:00 am to 5:30
pm Eastern Time. For technical inquiries, contact Elizabeth Corr or
Paul S. Berger, Ph.D.(Microbiology), Office of Ground Water and
Drinking Water (MC 4607), U.S. Environmental Protection Agency, 401 M
Street SW, Washington DC 20460; telephone (202) 260-8907 (Corr) or
(202) 260-3039 (Berger).
Regional Contacts
Region I. Kevin Reilly, Water Supply Section, JFK Federal Bldg., Room
203, Boston, MA 02203, (617) 565-3616
II. Michael Lowy, Water Supply Section, 290 Broadway, 24th Floor, New
York, NY 10007-1866, (212) 637-3830
III. Jason Gambatese, Drinking Water Section (3WM41), 841 Chestnut
Building, Philadelphia, PA 19107, (215) 566-5759
IV. David Parker, Water Supply Section, 345 Courtland Street, Atlanta,
GA 30365, (404)562-9460
V. Kimberly Harris (micro), Miguel Del Toral (DBP), Water Supply
Section, 77 W. Jackson Blvd., Chicago, IL 60604, (312) 886-4239
(Harris), (312) 886-5253 (Del Toral)
VI. Blake L. Atkins, Team Leader, Water Supply Section, 1445 Ross
Avenue, Dallas, TX 75202, (214) 665-2297
VII. Stan Calow, State Programs Section, 726 Minnesota Ave., Kansas
City, KS 66101, (913) 551-7410
VIII. Bob Clement, Public Water Supply Section (8WM-DW), 999 18th
Street, Suite 500, Denver, CO 80202-2466, (303) 312-6653
IX. Bruce Macler, Water Supply Section, 75 Hawthorne Street, San
Francisco, CA 94105, (415) 744-1884
X. Wendy Marshall, Drinking Water Unit, 1200 Sixth Avenue (OW-136),
Seattle, WA 98101, (206) 553-1890.
SUPPLEMENTARY INFORMATION:
Regulated entities. Entities potentially regulated by the IESWTR
are public water systems that use surface water and serve at least
10,000 people. Regulated categories and entities include:
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Category Examples of regulated entities
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Public Water System.................... PWSs that use surface water and
serve at least 10,000 people.
State Governments...................... State government offices that
regulate drinking water.
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[[Page 59487]]
This table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by the
IESWTR. This table lists the types of entities that USEPA is now aware
could potentially be regulated by the rule. Other types of entities not
listed in this table could also be regulated. To determine whether your
facility may be regulated by this action, you should carefully examine
the applicability criteria outlined under Alternatives A and B in
Sec. 141.70 of the proposed rule (59 FR 38832, July 29, 1994).
If you have questions regarding the applicability of the IESWTR to
a particular entity, contact one of the persons listed in the preceding
FOR FURTHER INFORMATION CONTACT section.
Additional Information for Commenters. The Agency requests that
commenters follow the following format: type or print comments in ink,
and cite, where possible, the paragraph(s) in this Notice to which each
comment refers. Commenters should use a separate paragraph for each
method or issue discussed. Electronic comments must be submitted as a
WP5.1 or WP6.1 file or as an ASCII file avoiding the use of special
characters and any form of name or title of the Federal Register.
Comments and data will also be accepted on disks in WordPerfect in 5.1
or WP6.1 or ASCII file format. Electronic comments on this Notice may
be filed online at many Federal Depository Libraries. Commenters who
want EPA to acknowledge receipt of their comments should include a
self-addressed, stamped envelope. No facsimiles (faxes) will be
accepted.
Availability of Record. The record for this Notice, which includes
supporting documentation as well as printed, paper versions of
electronic comments, is available for inspection from 9 to 4 p.m.,
Monday through Friday, excluding legal holidays at the Water Docket,
U.S. EPA Headquarters, 401 M. St., S.W. Washington, D.C. 20460. For
access to docket materials, please call 202/260-3027 to schedule an
appointment and obtain the room number.
Copyright Permission. Supporting documentation reprinted in this
document from copyrighted material may be reproduced or republished
without restriction in accordance with 1 CFR 2.6.
List of Abbreviations Used in This Document
ASCE--American Society of Civil Engineers
ASTM--American Society for Testing Materials
AWWA--American Water Works Association
C--the residual concentration of disinfectant, mg/L
CDC--Centers for Disease Control
CFE--Combined Filter Effluent
CFR--Code of Federal Regulations
CPE--Comprehensive Performance Evaluation
CT--the residual concentration of disinfectant multiplied by the
contact time
DOC--dissolved organic carbon
ESWTR--Enhanced Surface Water Treatment Rule
FACA--Federal Advisory Committee Act
gpm/sf--gallons per minute per square foot
HAA5--Haloacetic acids (monochloroacetic, dichloroacetic,
trichloroacetic, monobromoacetic, and dibromoacetic acids)
HAV--hepatitis A virus
hrs--hours
ICR--Information Collection Rule
IESWTR--Interim Enhanced Surface Water Treatment Rule
IFA--Individual Filter Assessment
IFE--Individual Filter Effluent
ISO--International Standards Organization
k--the pseudo first-order reaction rate constant
L--liter
Log Inactivation--logarithm of (No/NT)
Log--logarithm (common, base 10)
LTESWTR--Long Term Enhanced Surface Water Treatment Rule
MCL--Maximum Contaminant Level
MCLG--Maximum Contaminant Level Goal
M-DBP--Microbial and Disinfectants/Disinfection Byproducts
mg/L--milligram per liter
mg-min/L--milligram minutes per liter
MMWR--Morbidity and Mortality Weekly Report
mW-s/cm2--milliwatt seconds per square centimeter
No--the initial viable concentration of microorganisms
NPDWR--National Primary Drinking Water Regulation
NT--the concentration of surviving microorganisms at time T
NTU--nephelometric turbidity unit
deg.C--degrees centigrade
PE--Performance Evaluation
pH--negative logarithm of the effective hydrogen-ion concentration
PV1--poliovirus 1
PV3--poliovirus 3
PWS--Public Water System
RSD--Relative Standard Deviation
SAB--Science Advisory Board
SDWA--Safe Drinking Water Act
T--the contact time, second or minute
TOC--total organic carbon
TTHM--Total Trihalomethanes
TWG--Technical Work Group
UV--ultraviolet
x--log removal Reduction by 1/10**x
Table of Contents
I. Introduction and Background
A. Existing regulations
1. Surface Water Treatment Rule
2. Total Trihalomethane MCL
3. Total Coliform Rule
4. Information Collection Rule
B. Public health concerns to be addressed
C. Statutory provisions
1. SDWA and 1986 provisions
2. Changes to initial provisions and new mandates
D. Regulatory negotiation process
E. Information Collection Rule
F. Formation of 1997 Federal Advisory Committee
G. Overview of 1994 proposed IESWTR
1. Summary of major elements
2. Alternative treatment requirements
3. Possible supplemental treatment requirements
a. uncovered finished water reservoirs
b. cross connection control program
c. State notification of high turbidity levels
4. Other related issues
II. New Information and Key Issues To Be Addressed
A. MCLG for Cryptosporidium
1. Summary of 1994 proposal and public comments
2. New data and perspectives
3. Advisory Committee recommendations and related issues
B. Removal of Cryptosporidium by filtration
1. Summary of 1994 proposal and public comments
2. New data and perspectives
a. rapid granular filtration
b. other filtration technologies
c. multiple barrier approach
3. Advisory Committee recommendations and related issues
C. Turbidity control
1. Summary of 1994 proposal as it relates to turbidity issues
and public comments
2. New data and perspectives
a. 95th percentile and maximum turbidity levels of composite
filtered water
b. individual filter performance
c. turbidity measurement
3. Advisory Committee recommendations and related issues
D. Disinfection benchmark for Stage I DBP MCLs
1. Applicability
2. Developing the profile and benchmark
3. State review
4. Guidance
5. Request for public comment
E. Definition of ground water under direct influence of surface
water (GWUDI)--inclusion of Cryptosporidium in the definition
1. Summary of 1994 proposal and public comments
2. Overview of existing guidance
3. Summary of new data and perspectives
[[Page 59488]]
4. Request for public comment
F. Inclusion of Cryptosporidium in watershed control requirements
1. Summary of 1994 proposal and public comments
2. Overview of existing guidance
3. Summary of new data and perspectives
G. Sanitary survey requirements
1. Summary of 1994 proposal
2. Overview of existing regulations and guidance
3. New developments
4. Advisory Committee recommendations and related issues
H. Covered finished water reservoirs
1. Summary of 1994 proposal and public comments
2. Overview of existing information
3. Request for public comment
I. Cross connection control program
1. Summary of 1994 proposal and public comments
2. Overview of existing information
3. Request for public comment
J. Recycling filter backwash water and filtering to waste
1. Filter backwash recycle configuration
2. State drinking water regulations
3. Literature overview of standards of practice
4. Filter-to-waste
5. Request for public comment
K. Certification criteria for water plant operators
L. Regulatory compliance schedule and other compliance-related
issues
1. Regulatory compliance schedule
2. Compliance violations and State primacy obligations
3. Compliance with current regulations
M. Disinfection studies
1. New Giardia inactivation studies at high pH levels
2. Effectiveness of different disinfectants on Cryptosporidium
3. New virus inactivation studies
III. Economic Analysis of M-DBP Advisory Committee Recommendations
A. Overview of RIA for proposed rule
B. What's changed since proposed rule
C. Summary of cost analysis
1. Total national costs
2. Household costs
D. Cost of turbidity performance criteria & associated monitoring
1. System level impact analysis
2. National impact analysis
a. decision tree
b. utility costs
c. State costs
E. Disinfection benchmark
1. Decision tree
2. Utility costs
3. State costs
F. Sanitary surveys
G. Summary of benefits analysis
IV. National Technology Transfer and Advancement Act
I. Introduction and Background
A. Existing Regulations
1. Surface Water Treatment Rule
Under the Surface Water Treatment Rule (SWTR)(54 FR 27486, June 29,
1989), USEPA set maximum contaminant level goals of zero for Giardia
lamblia, viruses, and Legionella; and promulgated national primary
drinking water regulations for all public water systems (PWSs) using
surface water sources or ground water sources under the direct
influence of surface water. The SWTR includes treatment technique
requirements for filtered and unfiltered systems that are intended to
protect against the adverse health effects of exposure to Giardia
lamblia, viruses, and Legionella, as well as many other pathogenic
organisms. Briefly, those requirements include (1) removal or
inactivation of 3 logs (99.9%) for Giardia and 4 logs (99.99%) for
viruses; (2) combined filter effluent performance of 5 NTU as a maximum
and 0.5 NTU at 95th percentile monthly, based on 4-hour monitoring for
treatment plants using conventional treatment or direct filtration
(with separate standards for other filtration technologies); and (3)
watershed protection and other requirements for unfiltered systems.
2. Total Trihalomethane MCL
USEPA set an interim Maximum Contaminant Level (MCL) for total
trihalomethanes (TTHM) of 0.10 mg/l as an annual average in November
1979 (44 FR 68624). This standard was based on the need to balance the
requirement for continued disinfection of water to reduce exposure to
pathogenic microorganisms while simultaneously lowering exposure to
disinfection byproducts which might be carcinogenic to humans.
The interim TTHM standard only applies to any PWSs (surface water
and/or ground water) serving at least 10,000 people that add a
disinfectant to the drinking water during any part of the treatment
process. At their discretion, States may extend coverage to smaller
PWSs. However, most States have not exercised this option. About 80
percent of the PWSs, serving populations of less than 10,000, are
served by ground water that is generally low in THM precursor content
(USEPA, 1979) and which would be expected to have low TTHM levels even
if they disinfect.
3. Total Coliform Rule
The Total Coliform Rule (54 FR 27544; June 29, 1989), revised in
June 1989 and effective on December 31, 1990 applies to all public
water systems (USEPA, 1989b). This regulation sets compliance with the
Maximum Contaminant Level (MCL) for total coliforms as follows. For
systems that collect 40 or more samples per month, no more than 5.0% of
the samples may be total coliform-positive; for those that collect
fewer than 40 samples, only one sample may be total coliform-positive.
If a system exceeds the MCL for a month, it must notify the public
using mandatory language developed by the USEPA. The required
monitoring frequency for a system ranges from 480 samples per month for
the largest systems to once annually for certain of the smallest
systems. All systems must have a written plan identifying where samples
are to be collected. In addition, systems are required to conduct
repeat sampling after a positive sample.
The Total Coliform Rule also requires each system that collects
fewer than five samples per month to have the system inspected every 5
years (10 years for certain types of systems using only protected and
disinfected ground water.) This on-site inspection (referred to as a
sanitary survey) must be performed by the State or by an agent approved
by the State.
4. Information Collection Rule
The Information Collection Rule (ICR) is a monitoring and data
reporting rule that was promulgated on May 14, 1996 (61 FR 24354)
(USEPA, 1996b). The purpose of the ICR is to collect occurrence and
treatment information to evaluate the need for possible changes to the
current Surface Water Treatment Rule and existing microbial treatment
practices and to evaluate the need for future regulation for
disinfectants and DBPs. The ICR will provide USEPA with additional
information on the national occurrence in drinking water of (1)
chemical byproducts that form when disinfectants used for microbial
control react with compounds already present in source water and (2)
disease-causing microorganisms, including Cryptosporidium, Giardia, and
viruses. The ICR will also collect engineering data on how PWSs
currently control such contaminants. This information is being
collected because the regulatory negotiation on disinfectants and DBPs
concluded that additional information was needed to assess the
potential health problem created by the presence of DBPs and pathogens
in drinking water and to assess the extent and severity of risk in
order to make sound regulatory and public health decisions. The ICR
will also provide information to support regulatory impact analyses for
various regulatory options, and to help develop monitoring strategies
for cost effectively implementing regulations.
B. Public Health Concerns To Be Addressed
In 1990, USEPA's Science Advisory Board (SAB), an independent panel
of experts established by Congress, cited
[[Page 59489]]
drinking water contamination as one of the most important environmental
risks and indicated that disease-causing microbial contaminants (i.e.,
bacteria, protozoa and viruses) are probably the greatest remaining
health risk management challenge for drinking water suppliers (USEPA/
SAB 1990). This view was prompted by the SAB's concern about the number
of waterborne disease outbreaks in the U.S. Between 1980 and 1994, 379
waterborne disease outbreaks were reported, with over 500,000 cases of
disease. During this period, a number of agents were implicated as the
cause, including protozoa, viruses and bacteria, as well as several
chemicals. Most of the cases (but not outbreaks) were associated with
surface water, and specifically with a single outbreak of
cryptosporidiosis in Milwaukee (over 400,000 cases) (Craun, Pers. Comm.
1997a).
The number of waterborne disease outbreaks and cases is, however,
probably much greater than that recorded because the vast majority of
waterborne disease is probably not reported. Few States have an active
outbreak surveillance program and disease outbreaks are often not
recognized in a community or, if recognized, are not traced to the
drinking water source. This situation is complicated by the fact that
the vast majority of people experiencing gastrointestinal illness
(predominantly diarrhea) do not seek medical attention. For those who
do, physicians generally cannot attribute gastrointestinal illness to
any specific origin such as a drinking water source. An unknown but
probably significant portion of waterborne disease is endemic, i.e.,
not associated with an outbreak, and thus is even more difficult to
recognize.
One of the key regulations USEPA has developed and implemented to
counter pathogens in drinking water is the SWTR. Among its provisions,
the rule requires that a public water system have sufficient treatment
to reduce the source water concentration of Giardia and viruses by at
least 99.9% (3 logs) and 99.99% (4 logs), respectively.
The goal of the SWTR is to reduce risk to less than one infection
per year per 10,000 people (10-4). However, one of the
SWTR's shortcomings is that the source waters of some systems have high
pathogen concentrations that, when reduced by the levels required under
the rule, still may not meet a common health goal (e.g.,
10-4).
Another shortcoming of the SWTR is that the rule does not
specifically control for the protozoan Cryptosporidium. The first
report of a recognized outbreak caused by Cryptosporidium was published
during the development of the SWTR (D'Antonio et al., 1985). Other
outbreaks caused by this pathogen have since been reported both in the
United States and other countries (Smith et al.,1988; Hayes et al.,
1989; Levine and Craun, 1990; Moore et al., 1993; Craun, 1993). A
particular public health challenge is that simply increasing existing
disinfection levels above those most commonly practiced in the United
States today does not appear to be an effective strategy for
controlling Cryptosporidium.
In addition to these issues, there is another potentially counter-
balancing public health concern. The disinfectants used to control
microbial pathogens may produce toxic or carcinogenic disinfection
byproducts (DBPs) when they react with organic chemicals in the source
water. Thus, an important question facing water supply professionals is
how to minimize the risk from both microbial pathogens and DBPs
simultaneously.
At the time the SWTR was promulgated, USEPA had limited data
concerning Giardia and Cryptosporidium occurrence in source waters and
treatment efficiencies. The 3-log removal/inactivation of Giardia
lamblia and 4-log removal/inactivation of enteric viruses required by
the SWTR were developed to provide protection from most pathogens in
source waters. However, additional data has become available since
promulgation of the SWTR concerning source water occurrence and
treatment efficiencies for Giardia, as well as for Cryptosporidium
(LeChevallier et al. 1991 a,b). A major concern is that if systems
currently provide four or more logs of removal/inactivation for
Giardia, such systems might reduce existing levels of disinfection to
more easily meet new DBP regulations, and thus only marginally meet the
three-log removal/inactivation requirement for Giardia lamblia
specified in the current SWTR. Depending upon source water Giardia
concentrations, such treatment changes could lead to significant
increases in microbial risk (Regli et al., 1993; Grubbs et al., 1992;
USEPA, 1994b).
C. Statutory Provisions
1. SDWA and 1986 Provisions
The Safe Drinking Water Act (SDWA or the Act), as amended in 1986,
requires USEPA to publish a ``maximum contaminant level goal'' (MCLG)
for each contaminant which, in the judgement of the USEPA
Administrator, ``may have any adverse effect on the health of persons
and which are known or anticipated to occur in public water systems''
(Section 1412(b)(3)(A)). MCLGs are to be set at a level at which ``no
known or anticipated adverse effect on the health of persons occur and
which allows an adequate margin of safety'' (Section 1412(b)(4)).
The Act also requires that at the same time USEPA publishes an
MCLG, which is a non-enforceable health goal, it also must publish a
National Primary Drinking Water Regulation (NPDWR) that specifies
either a maximum contaminant level (MCL) or treatment technique
(Sections 1401(1) and 1412(a)(3)). USEPA is authorized to promulgate a
NPDWR ``that requires the use of a treatment technique in lieu of
establishing a MCL,'' if the Agency finds that ``it is not economically
or technologically feasible to ascertain the level of the
contaminant''.
Section 1414 (c) of the Act requires each owner or operator of a
public water system to give notice to the persons served by the system
of any failure to comply with an MCL or treatment technique requirement
of, or testing procedure prescribed by, a NPDWR and any failure to
perform monitoring required by section 1445 of the Act.
Section 1412(b)(7)(C) of the SDWA requires the USEPA Administrator
to publish a NPDWR ``specifying criteria under which filtration
(including coagulation and sedimentation, as appropriate) is required
as a treatment technique for public water systems supplied by surface
water sources''. In establishing these criteria, USEPA is required to
consider ``the quality of source waters, protection afforded by
watershed management, treatment practices (such as disinfection and
length of water storage) and other factors relevant to protection of
health''. This section of the Act also requires USEPA to promulgate a
NPDWR requiring disinfection as a treatment technique for all public
water systems and a rule specifying criteria by which variances to this
requirement may be granted.
2. Changes to Initial Provisions and New Mandates
In 1996, Congress reauthorized the Safe Drinking Water Act. Several
of the 1986 provisions discussed above were renumbered and augmented
with additional language, while other sections mandate new drinking
water requirements. These modifications, as well as new provisions, are
detailed below.
As part of the 1996 amendments to the Safe Drinking Water Act (the
Amendments), USEPA's general
[[Page 59490]]
authority to set a MCLG and NPDWR was modified to apply to contaminants
that may ``have an adverse effect on the health of persons'', that are
``known to occur or there is a substantial likelihood that the
contaminant will occur in public water systems with a frequency and at
levels of public health concern'', and for which ``in the sole
judgement of the Administrator, regulation of such contaminant presents
a meaningful opportunity for health risk reduction for persons served
by public water systems' (1986 SDWA Section 1412 (b)(3)(A) stricken and
amended with 1412(b)(1)(A)).
The Amendments also require that USEPA, when proposing a NPDWR that
includes an MCL or treatment technique, publish and seek public comment
on health risk reduction and cost analyses. The Amendments also require
USEPA to take into consideration the effects of contaminants upon
sensitive subpopulations (i.e. infants, children, pregnant women, the
elderly, and individuals with a history of serious illness), and other
relevant factors. (Section 1412 (b)(3)(C)).
The 1996 Amendments also newly require USEPA to promulgate an
Interim Enhanced SWTR and a Stage I Disinfectants and Disinfection
Byproducts Rule by November 1998. In addition, the 1996 Amendments
require USEPA to promulgate a Final Enhanced SWTR and a Stage 2
Disinfection Byproducts Rule by November 2000 and May 2002,
respectively (Section 1412(b)(2)(C)).
Under the Amendments of 1996, recordkeeping requirements were
modified to apply to ``every person who is subject to a requirement of
this title or who is a grantee'' (Section 1445 (a)(1)(A)). Such persons
are required to ``establish and maintain such records, make such
reports, conduct such monitoring, and provide such information as the
Administrator may reasonably require by regulation . . .''.
D. Regulatory Negotiation Process
In 1992 USEPA initiated a negotiated rulemaking to develop a
disinfectants/disinfection byproducts rule. The negotiators included
representatives of State and local health and regulatory agencies,
public water systems, elected officials, consumer groups and
environmental groups. The Committee met from November 1992 through June
1993.
Early in the process, the negotiators agreed that large amounts of
information necessary to understand how to optimize the use of
disinfectants to concurrently minimize microbial and DBP risk on a
plant-specific basis were unavailable. Nevertheless, the Committee
agreed that USEPA propose a disinfectants/disinfection byproducts rule
to extend coverage to all community and nontransient noncommunity water
systems that use disinfectants. This rule proposed to reduce the
current TTHM MCL, regulate additional disinfection byproducts, set
limits for the use of disinfectants, and reduce the level of organic
compounds in the source water that may react with disinfectants to form
byproducts.
One of the major goals addressed by the Committee was to develop an
approach that would reduce the level of exposure from disinfectants and
DBPs without undermining the control of microbial pathogens. The
intention was to ensure that drinking water is microbiologically safe
at the limits set for disinfectants and DBPs and that these chemicals
do not pose an unacceptable risk at these limits.
Following months of intensive discussions and technical analysis,
the Committee recommended the development of three sets of rules: a
two-staged Disinfectants/Disinfection Byproduct Rule (proposal: 59 FR
38668, July 29, 1994) (USEPA, 1994a), an ``interim'' ESWTR (proposal:
59 FR 38832, July 29, 1994) (USEPA, 1994b), and an Information
Collection rule (proposal: 59 FR 6332, February 10, 1994) (USEPA,
1994c). The IESWTR would only apply to systems serving 10,000 people or
more. The Committee agreed that a ``long-term'' ESWTR (LTESWTR) would
be needed for systems serving fewer than 10,000 people when the results
of more research and water quality monitoring became available. The
LTESWTR could also include additional refinements for larger systems.
The approach in developing these proposals considered the
constraints of simultaneously treating water to control for both
microbial contaminants and DBPs. As part of this effort, the
Negotiating Committee concluded that the SWTR may need to be revised to
address health risk from high densities of pathogens in poorer quality
source waters and from the protozoan, Cryptosporidium. The Committee
also agreed that the schedules for IESWTR and LTESWTR should be
``linked'' to the schedule for the Stage 1 DBP Rule to assure
simultaneous compliance and a balanced risk-risk based implementation.
The Committee agreed that additional information on health risk,
occurrence, treatment technologies, and analytical methods needed to be
developed in order to better understand the risk-risk tradeoff, and how
to accomplish an overall reduction in risk.
Finally the Negotiating Committee agreed that to develop a
reasonable set of rules and to understand more fully the limitations of
the current SWTR, additional field data were critical. Thus, a key
component of the regulation negotiation agreement was the promulgation
of the Information Collection Rule (ICR) noted above and described in
more detail below.
E. Information Collection Rule
As stated above, the ICR established monitoring and data reporting
requirements for large public water systems serving populations over
100,000. About 350 PWSs operating 500 treatment plants are involved in
the data collection effort. Under the ICR, these PWSs monitor their
source water for bacteria, viruses, and protozoa (surface water sources
only); water quality factors affecting DBP formation; and DBPs within
the treatment plant and in the distribution system. In addition, PWSs
must provide operating data and a description of their treatment plan
design. Finally, a subset of PWSs perform treatment studies, using
either granular activated carbon or membrane processes, to evaluate DBP
precursor removal. Monitoring for treatment study applicability began
in September 1996. The remaining occurrence monitoring began in July
1997.
The initial intent of the ICR was to collect monitoring data and
other information for use in developing the Stage 2 DBPR and IESWTR and
to estimate national costs for various treatment options. However,
because of delays in promulgating the ICR and technical difficulties
associated with laboratory approval and review of facility sampling
plans, most ICR monitoring did not begin until July 1, 1997. As a
result of this delay and the new Stage 1 DBPR and IESWTR deadlines
specified in the 1996 SDWA amendments, ICR data will not be available
for analysis in connection with these rules. In place of the ICR data,
the Agency has worked with stakeholders to identify additional data
developed since 1994 that can be used in components of these rules.
USEPA intends to continue to work with stakeholders in analyzing and
using the comprehensive ICR data and research for developing subsequent
revisions to the SWTR and the Stage 2 DBP Rule.
F. Formation of 1997 Federal Advisory Committee
In May 1996, the Agency initiated a series of public informational
meetings to exchange information on issues
[[Page 59491]]
related to microbial and disinfectants/disinfection byproducts
regulations. To help meet the deadlines for the IESWTR and Stage 1 DBPR
established by Congress in the 1996 SDWA Amendments and to maximize
stakeholder participation, the Agency established the Microbial and
Disinfectants/Disinfection Byproducts (M-DBP) Advisory Committee under
the Federal Advisory Committee Act (FACA) on February 12, 1997, to
collect, share, and analyze new information and data, as well as to
build consensus on the regulatory implications of this new information.
The Committee consists of 17 members representing USEPA, State and
local public health and regulatory agencies, local elected officials,
drinking water suppliers, chemical and equipment manufacturers, and
public interest groups.
The Committee met five times, in March through July 1997, to
discuss issues related to the IESWTR and Stage 1 DBPR. Technical
support for these discussions was provided by a Technical Work Group
(TWG) established by the Committee at its first meeting in March 1997.
The Committee's activities resulted in the collection, development,
evaluation, and presentation of substantial new data and information
related to key elements of both proposed rules. The Committee reached
agreement on the following major issues discussed in this Notice and
the Notice for the Stage 1 DBPR published elsewhere in today's Federal
Register: (1) MCLs for TTHMs, HAA5 and bromate; (2) requirements for
enhanced coagulation and enhanced softening (as part of DBP control);
(3) microbial benchmarking/profiling to provide a methodology and
process by which a PWS and the State, working together, assure that
there will be no significant reduction in microbial protection as the
result of modifying disinfection practices in order to meet MCLs for
TTHM and HAA5; (4) disinfection credit; (5) turbidity; (6)
Cryptosporidium MCLG; (7) removal of Cryptosporidium; (8) role of
Cryptosporidium inactivation as part of a multiple barrier concept and
(9) sanitary surveys. The Committee's recommendations to USEPA on these
issues were set forth in an Agreement In Principle document dated July
15, 1997. This document is included with this notice as Appendix 1.
G. Overview of IESWTR 1994 Proposal
1. Summary of Major Elements
As part of the IESWTR July 29, 1994, Federal Register notice (59 FR
38832), USEPA proposed to revise the SWTR to provide additional
protection against pathogens in drinking water. USEPA proposed to set
the MCLG for Cryptosporidium at zero based on animal studies and human
epidemiology studies of waterborne outbreaks of cryptosporidiosis. The
proposal also focused on treatment requirements for the waterborne
pathogens Giardia lamblia, Cryptosporidium, Legionella and viruses that
would apply to all public water systems that use surface water or
ground water under the influence of surface water and serve 10,000
people or more. Major features of the proposal included a stricter
watershed control requirement for systems using surface water that wish
to avoid filtration; a change in the definition of ground water under
the influence of surface water to include the presence of
Cryptosporidium; a periodic sanitary survey requirement for all systems
using surface water or ground water under the influence of surface
water; and several alternative requirements, described below, for
augmenting treatment control of Giardia lamblia, Cryptosporidium, and
viruses. USEPA also requested comment on several supplemental
provisions and on other related issues, described below.
2. Alternative Treatment Requirements
USEPA proposed five treatment alternatives for controlling Giardia
lamblia, Cryptosporidium, and viruses. Each alternative included
several options. Alternative A addressed enhanced treatment for Giardia
lamblia only. Alternatives B and C addressed treatment for
Cryptosporidium only. Alternative D addressed enhanced treatment for
viruses only. Alternative E would maintain existing levels of treatment
for Giardia lamblia and viruses.
a. Alternative A. Enhanced treatment for Giardia lamblia. The SWTR
currently requires a 99.9 percent (3-log) removal/inactivation of
Giardia lamblia for all surface waters, regardless of Giardia lamblia
cyst concentrations in the source water. Under Alternative A, the
minimum level of treatment a system would be required to provide (e.g.,
3, 4, 5 or 6 log removal/inactivation) would depend on the Giardia
lamblia density in the source water as determined by monitoring over
some specified interval of time. The level of prescribed treatment for
a particular system would correspond to providing water below an annual
risk level for Giardia lamblia infections (e.g. 10-4).
b. Alternative B. Specific Treatment for Cryptosporidium. USEPA
also proposed a treatment technique for Cryptosporidium similar to the
proposal for Giardia under Alternative A, such that the required level
of Cryptosporidium treatment for any particular system would depend on
the density of Cryptosporidium in the source water.
c. Alternative C. 99% (2-log) removal of Cryptosporidium. Under
this alternative, USEPA would require systems to achieve at least a 99%
(2-log) removal of Cryptosporidium by filtration (with pretreatment).
The 2-log level was based on the premise that a 3-log level (as
currently required for Giardia removal/inactivation) is not
economically or technologically possible, since data suggests that
Cryptosporidium is consistently more resistant to disinfection than is
Giardia. USEPA indicated that it would continue to assess new field and
laboratory data to control Cryptosporidium by physical removal and
disinfection for consideration in subsequent microbial regulations.
d. Alternative D. Specific disinfection treatment for viruses. The
SWTR required systems to achieve a four-log removal/inactivation of
viruses. This is to be achieved through a combination of filtration and
disinfection or, for systems not required to filter their source
waters, by disinfection alone. However, this level of treatment may not
be adequate to achieve a particular health risk (e.g., 10-4
infections/yr/person) for viruses. Viruses are of particular concern,
given that one or several virus particles may be infectious (Regli et
al.,1991) and that several enteric viruses are associated with
relatively high mortality rates (Bennett et al., 1987). Failure or
impairment of filtration performance could allow substantial pathogen
contamination of drinking water, particularly if the disinfection
barrier following filtration is minimal.
Alternative D would require that systems provide sufficient
disinfection such that disinfection alone would achieve at least a 0.5-
log inactivation of Giardia lamblia or, alternatively, a 4-log
inactivation of viruses. This proposed approach would be independent of
the level of physical removal or the source water density of viruses.
If the filtration process was able to remove three logs of Giardia
lamblia, a system would still have to provide at least an additional
0.5-log inactivation of Giardia lamblia or 4-log inactivation of
viruses by disinfection.
e. Alternative E. No change to existing SWTR treatment requirements
for Giardia lamblia and viruses. Alternative E maintains existing SWTR
levels of
[[Page 59492]]
treatment for Giardia lamblia and viruses. USEPA could regulate
Cryptosporidium directly (e.g., Alternative C above) or make a finding
that existing SWTR filtration and disinfection requirements are
adequate to control this organism.
3. Possible Supplemental Treatment Requirements
USEPA also requested comment on three supplemental requirements
regarding uncovered finished water reservoirs, cross connection control
and State notification of turbidity levels.
a. Uncovered Finished Water Reservoirs. As part of the 1994
proposal, USEPA requested comment on possible supplemental requirements
for uncovered finished water reservoirs. The Agency noted that USEPA
guidelines recommend that all finished water reservoirs be covered
(USEPA, 1991a) and that the American Water Works Association (AWWA)
also has issued a policy statement that strongly supports the covering
of such reservoirs (AWWA, 1993).
b. Cross Connection Control Program. USEPA requested comment on
whether to require States or public water systems to have cross
connection control programs. Plumbing cross-connections are actual or
potential connections between a potable and non-potable water supply
(USEPA, 1989a). According to Craun (1991), 24% of the waterborne
disease outbreaks that occurred during 1981-1990 were caused by water
contamination in the distribution system, primarily as the result of
cross-connections and main repairs.
c. State Notification of High Turbidity Levels. USEPA also
requested comment on whether to require systems to notify the State as
soon as possible for persistent turbidity levels above the performance
standards or for any other situation that is not now a violation of the
turbidity standards. Under the SWTR, any time the turbidity of a
treatment plant's combined filter effluent exceeds 5 NTU the system
must notify the State as soon as possible, but no later than the end of
the next business day. In addition, the system must notify the public
as soon as possible, but in no case later than 14 days after the
violation.
USEPA indicated in the proposal that it was considering broadening
the requirement for State notification. The Agency suggested it might,
for example, require systems to notify the State as soon as possible if
at any point during the month it becomes apparent that a system will
violate the monthly 95th percentile turbidity performance standard
specified in the SWTR, rather than wait to the end of the month.
USEPA outlined a number of public health reasons for requiring
swift State notification for persistent turbidity levels. Pathogens may
accompany the turbidity particles that exit the filters, especially
with poor quality source waters. High turbidity levels in the filtered
water, even for a limited time, may represent a significant risk to the
public. USEPA's proposed approach was intended to allow States to
respond in controlling a potentially serious problem more quickly.
4. Other related issues. The Agency also requested comments on
other issues related to possible IESWTR options. A number of these are
listed below.
(a) To what extent should the ESWTR address the issue of recycling
filter backwash, given its potential for increasing the densities of
Giardia lamblia and Cryptosporidium on the filter?
(b) Should the ESWTR define minimum certification criteria for
surface water treatment plant operators? Currently the SWTR (40 CFR
141.70) requires such systems to be operated by ``qualified personnel
who meet the requirements specified by the State.''
(c) What criteria, if any, should the ESWTR include to ensure that
systems optimize treatment plant performance?
(d) Should turbidity performance criteria be modified? Should
criteria pertain to individual filters?
(e) Should the rule include a performance standard for particle
removal?
(f) Should the rule include a requirement for an early warning for
high turbidity?
(g) Under what conditions could systems be allowed different log
removal credits than is currently recommended in the SWTR Guidance
Manual?
(h) How should USEPA decide, in developing a Notice of Data
Availability, what treatment approach(es) is most suitable for
additional public comment?
II. New Information and Key Issues to be Addressed
A. MCLG for Cryptosporidium
1. Summary of 1994 Proposal and Public Comments
The July 29, 1994, Federal Register notice proposed to set the MCLG
for Cryptosporidium at zero. The purpose of the MCLG is to protect
public health. The reasons for this determination were based upon
animal studies and human epidemiology studies of waterborne outbreaks
of cryptosporidiosis.
Most commenters supported an MCLG of zero for Cryptosporidium.
Those who provided reasons stated that (1) a single cell could infect,
and data do not support a threshold dose below which an outbreak or
disease will not occur, (2) the organism is present in water and has
caused major waterborne disease outbreaks, and (3) it is consistent
with the goals set under the SWTR and Total Coliform Rule. Commenters
who opposed the proposed MCLG stated that USEPA needed more health risk
and organism/disease transmission data and better analytical methods
before setting an MCLG and regulating Cryptosporidium.
2. New data and Perspectives
Since publication of the proposed rule, results of a human feeding
study have become available. Dupont et al. (1995) fed 29 healthy
volunteers single doses ranging from 30 to 1 million C. parvum oocysts
obtained from a calf. Of the 16 volunteers who received 300 or more
oocysts, 88% became infected. Of the five volunteers who received the
lowest dose (30 oocysts), one became infected. The median infective
dose was 132 oocysts. According to a mathematical model based upon the
Dupont et al. data, 0.5% of a population exposed to an average dose of
one oocyst, would be expected to become infected. (Haas et al., 1996).
An important concern is that certain populations are at greater
risk of waterborne disease infection than others. These vulnerable
populations include the immunocompromised; children, especially the
very young; the elderly; and pregnant women (Gerba et al. 1996; Fayer
and Ungar 1986). The most significant segment within these vulnerable
populations with regard to cryptosporidiosis is people who are
immunocompromised. In patients with severely weakened immune systems,
(e.g cancer, AIDS patients), cryptosporidiosis can be serious, long-
lasting and sometimes fatal. There is concern about cryptosporidiosis
in immunocompromised individuals because currently there is no cure for
the disease.
C. parvum is the only Cryptosporidium species known for certain to
infect humans. One controversial report (the only one of its kind)
found evidence that C. baileyi, which infects birds, was present in the
stools and other autopsied organs of an immunodeficient patient
(Ditrich et al., 1991). There was no indication that Cryptosporidium
had been responsible in this instance for any adverse health effects.
C. parvum also infects many other mammals. While C. parvum is a
[[Page 59493]]
well-documented human pathogen, strain variation may occur and one
strain may cause infection and/or disease at a higher or lower
concentration than other strains. USEPA is currently funding research
[Cryptosporidium virulence study using different strains, Herbert
Dupont] to examine this issue.
There is some question about the taxonomy (i.e., classification) of
species within the genus Cryptosporidium. Up until 1980, classification
was based on the assumption that a particular species only infected one
type of animal. This assumption appears to be incorrect; hence other
appropriate taxonomy schemes have been suggested.
An important issue not directly related to the MCLG involves the
measurement of C. parvum in water. With current technology, it is often
very difficult to distinguish between viable and non-viable oocysts.
When Cryptosporidium is identified it is often not clear whether it is
C. parvum or another species. Several Cryptosporidium species look
similar to C. parvum and react to ``specific'' C. parvum stains in a
like manner (cross-reactions). In addition, it can be difficult to
distinguish Cryptosporidium from alga and invertebrate eggs (Clancy et
al. 1994)
3. Advisory Committee Recommendations and Related Issues
The M-DBP Federal Advisory Committee supported the proposed
establishment of a Cryptosporidium MCLG at zero. However, a key issue
identified by the Committee and public commenters is whether the MCLG
should be set at the genus level (i.e., Cryptosporidium), as proposed,
or at the more specific species level (i.e., C. parvum). Setting the
MCLG at the genus level would automatically include any Cryptosporidium
species other than C. parvum that is later found to be pathogenic to
humans. In contrast, setting an MCLG at the species level would
indicate that only C. parvum infects humans, and would also be
consistent with the approach taken under the SWTR for Giardia where the
MCLG is set at the species level (i.e., G. lamblia). USEPA has not
decided which approach is most appropriate and seeks public comment on
this issue.
As indicated above, USEPA's intent in establishing this MCLG at
zero is to protect public health. The Agency believes there is adequate
research data to support this determination. However, as noted above,
the Agency recognizes that there is scientific uncertainty on the issue
of Cryptosporidium taxonomy and on the question of cross reactions
between species. USEPA expects further clarification on this issue as
research continues, Cryptosporidium analytical methods improve, and
more is learned about the circumstances under which cross-reactivity
between species occurs. The Agency also wishes to emphasize that the
scope or specificity of the MCLG may be modified in the future to
reflect new research and additional information about particular
species that represent a significant risk to human health.
As part of this notice, USEPA requests comment on whether to
establish a Cryptosporidium MCLG at the genus level as proposed or at
the species level (i.e., Cryptosporidium vs. Cryptosporidium parvum).
USEPA also requests copies of any additional research, data or other
information related to this issue.
B. Removal of Cryptosporidium by Filtration
1. Summary of 1994 Proposal and Public Comments Received
One of USEPA's proposed treatment Alternatives (Alternative C)
would require filtered systems to achieve at least a 2 log removal of
Cryptosporidium oocysts. USEPA recognized that the proposed removal
level was based on limited data and therefore solicited comment on
whether other minimum removal levels might be appropriate.
Most commenters addressing the issue of treatment alternatives
supported Alternative C. Some commenters opposed any treatment
requirement greater than a 2 log removal due to a lack of better
understanding of dose-response, effectiveness of treatment, and
analyses to justify the higher treatment costs involved.
Other commenters referred to specific studies (Nieminski 1995;
Patania et al., 1995) that provided additional information on
Cryptosporidium removal. One commenter cited a study (Parker and Smith,
1993), where oocyst damage was observed after agitation with sand. This
study postulated that oocysts may be damaged as they pass through the
filtration media. This commenter also pointed to the lack of data on
cyst removal by full-scale plants and recommended that additional
research be conducted. Some commenters recognized the need to regulate
Cryptosporidium, but opposed having the level of treatment based upon
source water pathogen density (alternative B). One commenter indicated
that further implementation and evaluation of the adequacy of the SWTR
needs to occur before modifying it.
2. New Data and Perspectives
a. Rapid Granular Filtration. Table 1 summarizes research pertinent
to Cryptosporidium and Giardia lamblia removal efficiencies by rapid
granular filtration. Brief descriptions of these studies and a summary
of key points follow.
Table 1.--Cryptosporidium and Giardia Lamblia Removal Efficiencies by Rapid Granular Filtration
----------------------------------------------------------------------------------------------------------------
Type of treatment plant Log removal Experimental design Researcher
----------------------------------------------------------------------------------------------------------------
Conventional filtration plants... Crypt 2.7-5.9....... Pilot Plants....... Patania et al. 95.
Do........................... Giardia 3.4-5.8..... ......do........... Do.
Do........................... Crypt 2.3-3.0....... Pilot scale plant.. Nieminski/Ongerth 95.
Do........................... Giardia 3.3-3.4..... +full scale plant Do.
with seeded cysts/
oocysts.
Do........................... Crypt 2.7-3.1....... Pilot Plants....... Ongerth/Pecaroro 95.
Do........................... Giardia 3.1-3.5..... ......do........... Do.
Do........................... Crypt 2-2.5......... Full scale plants.. LeChevallier et al. 91b.
Do........................... Giardia 2-2.5....... Full scale plants.. LeChevallier et al. 91b.
Do........................... Crypt 2.3-2.5....... Full scale plants.. LeChevallier/Norton 92.
Do........................... Giardia 2.2-2.8..... ......do........... Do.
Do........................... Crypt 2-3........... Pilot scale plant.. Foundation for Water.
Research 94.
Do........................... Giardia and......... Full scale plant... Kelley et al. 95.
DoCrypt 1.5-2................ operation considered
ot optimized).
Direct filtration plants......... Crypt 1.5-4.0....... Pilot Plants....... Patania et al. 1995.
Do........................... Giardia 1.5-4.8..... ......do........... Do.
[[Page 59494]]
Do........................... Crypt 2.8-3.0....... ......do........... Nieminski/Ongerth 95.
Do........................... Giardia 3.3-3.9..... ......do........... Do.
Do........................... Crypt 2-3........... ......do........... West et al. 1994.
----------------------------------------------------------------------------------------------------------------
Patania, Nancy L; et al. 1995
Raw water turbidities were between 0.2 and 13. When treatment
conditions were optimized for turbidity and particle removal at four
different sites, Cryptosporidium removal ranged from 2.7 to 5.9 log and
Giardia removal ranged from 3.4 to 5.1 log during stable filter
operation. The median turbidity removal was 1.4 log, whereas the median
particle removal was 2 log. Median oocyst and cyst removal was 4.2 log.
A filter effluent turbidity of 0.1 NTU or less resulted in the most
effective cyst removal, by up to l log greater than when filter
effluent turbidities were greater than 0.1 NTU (within the 0.1 to 0.3
NTU range) (see Figures 1 and 2 below). Cryptosporidium removal rates
of less than 2.0 log (indicated in Figures 1 and 2) occurred at the end
of the filtration cycle.
Blackened data points in these figures represent data in which
oocysts were not detected in the filtered water. The log removal values
shown would be greater than indicated had the influent oocyst
concentration been sufficiently high to show oocyst detection in the
filtered water. The researchers also noted that removal of
Cryptosporidium was 0.4 to 0.9 log lower during filter ripening than
during stable filter operation; Giardia removal was generally 0.4 to
0.5 log lower during ripening. Cryptosporidium removal was 1.4 to 1.8
log higher for conventional treatment (including sedimentation) as
compared to direct filtration. Similarly, Giardia removal was 0.2 to
1.8 log higher. Figures 1 and 2 below show the log removal rates
discussed above.
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Nieminski, Eva C. and Ongerth, Jerry E. 1995
This study evaluated performance in a pilot plant and in a full
scale plant (not in operation during the time of the study) and
considered two treatment modes: direct filtration and conventional
treatment. The source water of the full scale plant had turbidities
typically between 2.5 and 11 NTU with a peak level of 28 NTU. The
source water of the pilot plant typically had turbidities of 4 NTU with
a maximum of 23 NTU. For the pilot plant, achieving filtered water
turbidities between 0.1-0.2 NTU, Cryptosporidium removals averaged 3.0
log for conventional treatment and 3.0 log for direct filtration, while
the respective Giardia removals averaged 3.4 log and 3.3 log. For the
full scale plant, achieving similar filtered water turbidities,
Cryptosporidium removal averaged 2.25 log for conventional treatment
and 2.8 log for direct filtration, while the respective Giardia
removals averaged 3.3 log for conventional treatment and 3.9 log for
direct filtration. Differences in performance between direct filtration
and conventional treatment by the full scale plant were attributed to
different source water quality during the filter runs.
Ongerth, Jerry E. and Pecoraro, J.P. 1995
This project used very low turbidity source waters (0.35 to 0.58
NTU). With optimal coagulation, 3 log removal for both cysts were
obtained. In one test run, where coagulation was intentionally
suboptimal, the removals were only 1.5 log for Cryptosporidium and 1.3
log for Giardia. This emphasized the importance of proper coagulation
for cyst removal even though the effluent turbidity was less than 0.5
NTU.
LeChevallier, Mark W. and Norton, William D. 1992
Source water turbidities ranged from less than 1 to 120 NTU.
Removals of Giardia and Cryptosporidium (2.2-2.8 log) were slightly
less than those reported by other researchers, possibly because full
scale plants were studied, under less ideal conditions than the pilot
plants. The participating treatment plants were in varying stages of
treatment optimization. Removal achieved a median of 2.5 log for
Cryptosporidium and Giardia.
LeChevallier, Mark W.; Norton, William D.; and Lee, Raymond G. 1991b
This study evaluated removal efficiencies for Giardia and
Cryptosporidium in 66 surface water treatment plants in 14 States and 1
Canadian province. Most of the utilities achieved between 2 and 2.5 log
removals for both Giardia and Cryptosporidium. When no cysts were
detected on the finished water below detection protozoan levels were
set at the detection limit for calculating removal efficiencies.
Foundation for Water Research 1994
Raw water turbidity ranged from 1 to 30 NTU. Cryptosporidium oocyst
removal was between 2 and 3 log. Investigators concluded that any
measure which reduced filter effluent
[[Page 59497]]
turbidity should reduce risk from Cryptosporidium. The importance in
selecting coagulants, dosages, and pH should not be overlooked. Apart
from turbidity, indicators of possible reduced efficiency for oocyst
removal would be increased color and dissolved metal ion coagulant
concentration in the effluent, for these are indications of reduced
efficiency of coagulation/ flocculation.
Kelley, M.B. et al. 1995
Protozoa removal was between 1.5 and 2 log. The authors speculated
that this low Cryptosporidium removal occurred because the coagulation
process was not optimized, though the finished water turbidity was less
than 0.5 NTU. Also, when cysts were not detected in the finished water
below detection values were assumed as filtered water concentration
levels.
West, Thomas; et al. 1994
Pilot scale direct filtration was used with anthracite mono-media
at filtration rates of 6 and 14 gpm/sq ft. Raw water turbidity was 0.3
to 0.7 NTU. Removal efficiencies for Cryptosporidium at both filtration
rates were 2 log during filter ripening (despite turbidity exceeding
0.2 NTU), and 2 to 3 log for the stable filter run, declining
significantly during particle breakthrough. When effluent turbidity was
less than 0.1 NTU, removal typically exceeded 2 log. Log removal of
Cryptosporidium generally exceeded that for particle removal.
Summary of Studies
The studies described above indicate that rapid granular
filtration, when operated under appropriate coagulation conditions and
optimized to achieve a filtered water turbidity level of less than 0.3
NTU, should achieve at least 2 log of Cryptosporidium removal. Removal
rates vary widely, up to almost 6 log, depending upon water matrix
conditions, filtered water turbidity effluent levels, and where and
when removal efficiencies are measured within the filtration cycle. The
highest log pathogen removal rates occurred in those pilot plants and
systems which achieved very low finished water turbidities (less than
0.1 NTU).
Members of the M-DBP Advisory Committee discussed that tighter
turbidity performance criteria would increase the likelihood of systems
achieving higher oocyst removal rates. As a general principle, members
of the M-DBP Advisory Committee indicated that if a utility were
required to achieve less than 0.3 NTU 95% of the time, it would target
substantially lower turbidity levels in order to have confidence that
it will not exceed the 0.3 level. This principle was also recognized by
the M-DBP Advisory Committee's Technical Work Group and served as a
technical basis for much of the Committee's discussion of turbidity
(i.e., that if the performance standard is 0.3 NTU systems would target
achieving less than 0.2 NTU 95 percent of the time).
The Patania and Nieminski/Ongerth studies as they relate to
finished water turbidity levels and log removal are particularly
relevant to this point. These particular studies involve finished water
turbidity at low levels in the same range as the finished water target
identified by the Committee. The associated removal of Cryptosporidium
at these turbidity levels was reliably in the range of 2 log or
greater.
Other key points discussed during the Advisory Committee's
deliberations related to the studies include:
As turbidity performance improves for treatment of a
particular water, there tends to be greater removal of Cryptosporidium.
Pilot plant study data in particular indicate high
likelihood of achieving at least 2 log removal when plant operation is
optimized to achieve low turbidity levels. Moreover, pilot studies
represented in the table tend to be for low-turbidity waters, which are
considered to be the most difficult to treat regarding particulate
removal and associated protozoan removal. Since high removal rates have
been demonstrated in pilot studies using lower-turbidity source waters,
it is likely that similar or higher removal rates would be achieved for
higher-turbidity source waters.
The evaluation of Cryptosporidium removal in full-scale
plants can be difficult in that this data includes many non-detects in
the finished water. In these cases, values assigned at the detection
limit will likely result in over-estimation of oocysts in the finished
water. This in turn means that removal levels will tend to be under-
estimated.
Another factor that contributes to differences among the
data is that some of the full-scale plant data comes from plants that
are not optimized, but that still meet existing SWTR requirements. In
such cases, oocyst removal may be less than 2 log. In those studies
that indicate that full-scale plants are achieving greater than 2 log
removal (LeChevallier studies in particular), the following
characteristics pertain:
--Substantial numbers of filtered water measurements resulted in oocyst
detections;
--Source water turbidity tended to be relatively high compared to some
of the other studies;
--A significant percentage of these systems were also achieving low
filtered water turbidities, substantially less than 0.5 NTU.
Removal of Cryptosporidium can vary significantly in the
course of the filtration cycle (i.e., at the start-up and end of filter
operations versus the stable period of operation, which is the
predominant period).
b. Other Filtration Technologies. Other filtration technologies
include slow sand and diatomaceous earth filtration. ``Technologies and
Costs for the Treatment of Microbial Contaminants in Potable Water
Supplies, October 1988'' by USEPA (1988) listed research studies
indicating that a well designed and operated plant using these
technologies is capable of 3-to 4-log removal of Giardia and viruses.
Recent findings appear in Table 2 below.
Table 2.--Cryptosporidium and Giardia Lamblia Removal Efficiencies
----------------------------------------------------------------------------------------------------------------
Type of treatment plant Log removal Experimental design Researcher
----------------------------------------------------------------------------------------------------------------
Slow Sand........................ Giardia >3.......... Pilot plant at 4.5 Schuller and Ghosh, 91.
to.
Crypt >3............ 16.5 degrees C.....
Crypt 4.5........... Full scale plant... Timms et al., 1995
Diatomaceous Earth............... Giardia >3.......... Pilot plant, Schuler and Ghosh, 90.
addition of.
Crypt >3............ coagulant increased
.................. removal beyond.....
.................. values shown.......
----------------------------------------------------------------------------------------------------------------
[[Page 59498]]
c. Multiple Barrier Approach.
The M-DBP Advisory Committee engaged in extensive discussion
regarding the adequacy of relying solely on physical removal to control
Cryptosporidium in drinking water supplies and on the need for
inactivation. There was a substantial absence of technical consensus on
how to or whether it is currently possible to adequately measure
Cryptosporidium inactivation efficiencies for various disinfection
technologies. This issue emerged as a significant impediment to
addressing inactivation in the IESWTR.
As part of the original 1994 proposal, USEPA included control
strategies that would entail the development of a map of inactivation
efficiencies for Cryptosporidium. As discussed later in Section M. of
this Notice, adequate information to develop such a map is not
available at this time. The Advisory Committee discussion recognized,
however, that inactivation requirements may be appropriate and
necessary under future regulatory scenarios and that physical removal
by filtration may not be sufficient under all circumstances or for all
source waters.
As part of the development process for the long term ESWTR, the
Advisory Committee recommended that USEPA request comment on a risk-
based proposal for Cryptosporidium embodying the multiple barrier
approach (e.g., source water protection, physical removal,
inactivation, etc.), including, where risks suggest appropriate,
inactivation requirements. In establishing the LTESWTR, the Committee
recommended that the following issues be evaluated:
--Data and research needs and limitations (e.g., occurrence, treatment,
viability, active disease surveillance, etc.);
--Technology and methods capabilities and limitations;
--Removal and inactivation effectiveness;
--Risk tradeoffs including risks of significant shifts in disinfection
practices;
--Cost considerations consistent with the SDWA;
--Reliability and redundancy of systems; and
--Consistency with the requirements of the Act.
3. Advisory Committee Recommendations and Related Issues
USEPA reiterates its request for comment on the following
recommendations of the M-DBP Advisory Committee.
All surface water systems that serve more than 10,000 people and
are required to filter must achieve at least a 2-log removal of
Cryptosporidium. Systems which use rapid granular filtration (direct
filtration or conventional filtration treatment-as currently defined
in the SWTR), and meet the turbidity requirements described in
section II.C. are assumed to achieve at least a 2-log removal of
Cryptosporidium. Systems which use slow sand filtration and
diatomaceous earth filtration and meet existing turbidity
performance requirements under the SWTR (less than 1 NTU for the
95th percentile or alternative criteria as approved by the State)
are assumed to achieve at least 2-logs removal of Cryptosporidium.
Systems may demonstrate that they achieve higher levels of
physical removal.
C. Turbidity Control
1. Summary of 1994 Proposal as it Relates to Turbidity Issues and
Public Comments
Finished water turbidity levels are currently regulated by USEPA
under the SWTR as a treatment technique to ensure removal of Giardia
and viruses. The SWTR requires systems to monitor the turbidity of the
combined filter effluent every four hours at each treatment plant.
Systems using direct filtration or conventional treatment must achieve
a combined filter effluent turbidity level of no more than 0.5 NTU in
95% of the measurements in each month and never exceed 5 NTU. Failure
of individual filters may allow pathogens to enter the distribution
system. However, the SWTR does not presently require systems to monitor
the effluent of individual filters.
As a treatment technique, turbidity is an indicator of filtration
performance. Treatment plants are, as noted above, required to meet
certain turbidity levels to meet the removal requirements for Giardia.
Although turbidity is not a direct indicator of health risk, a very low
turbidity level of the treated water is in general a good indicator of
effective Cryptosporidium and Giardia oocyst and cyst removal by rapid
granular filtration. USEPA continues to believe that turbidity is the
most readily measurable parameter to indicate filtration treatment
effectiveness.
A primary focus of the 1994 proposal was the establishment of
treatment requirements that would address public health risks from high
densities of pathogens in poor quality source waters and from the
waterborne pathogen Cryptosporidium. As discussed earlier in this
Notice, waterborne pathogens have caused significant disease outbreaks
in the United States. Approaches outlined in the 1994 proposal included
treatment requirements based on site-specific concentrations of
pathogens in source water and a proposed 2-log removal requirement for
Cryptosporidium by filtration.
USEPA also specifically requested comment on what criteria, if any,
should be included to ensure that systems optimize treatment plant
performance and on whether any of the existing turbidity performance
criteria should be modified (e.g., should systems be required to base
compliance with the turbidity standards on individual filter effluent
monitoring in lieu of or in addition to monitoring the confluence of
all filters; and should any performance standard value be changed). In
addition, the Agency requested comment in the 1994 proposal on possible
supplemental requirements for State notification of persistent high
turbidity levels (e.g., broadening the requirements for State
notification of turbidity exceedances).
Some comments suggested and supported a revised approach to the
IESWTR that would focus on optimizing existing water treatment
processes to provide insurance against microbial disease outbreak in
the absence of source water occurrence data. Another comment suggested
that current levels of treatment, including filtration, have a
sufficient degree of effectiveness in preventing transmission of
Cryptosporidium in drinking water.
One commenter suggested that turbidity performance standards should
not be modified until the SWTR has been further implemented. One
commenter suggested that decreases in turbidity standards or monitoring
after each filter should be voluntary unless scientific data
demonstrate otherwise. Another commenter suggested that individual
filters can be evaluated during sanitary surveys. Several commenters
supported tighter turbidity standards and monitoring of individual
filters. Suggested turbidity performance levels included 0.1 or less,
or 0.2 NTU as revised standards. Several commenters supported
monitoring of individual filters, with one suggesting backwashing of
filters when turbidity levels increase.
2. New Data and Perspectives
As presented in detail below, the M-DBP Advisory Committee's
recommendations to the Agency included tighter turbidity performance
criteria and individual filter monitoring requirements as part of the
IESWTR. These revised performance criteria, along with the individual
filter monitoring requirements, would better enable systems to
demonstrate that they meet a 2 log removal requirement for
Cryptosporidium. Because Cryptosporidium is exceptionally
[[Page 59499]]
resistant to inactivation using chlorine, physical removal by
filtration is extremely important in controlling this organism. Data
presented in the previous section of this Notice support modifications
to the existing turbidity requirements under the SWTR to enable systems
to demonstrate that they meet the proposed 2 log requirement.
The revised turbidity performance criteria would also contribute to
another of the IESWTR's key objectives, which is to establish a
microbial backstop to prevent significant increases in microbial risk
when systems implement new disinfection byproduct standards under the
Stage 1 DBPR. As indicated by data presented below, tighter turbidity
performance criteria would reflect actual current performance for a
substantial percentage of systems nationally. Revising the turbidity
criteria would effectively ensure that these systems continue to
perform at these levels (in addition to resulting in improved
performance by systems that currently meet the existing criteria but
that operate at levels higher than those suggested in the Advisory
Committee's recommendations). The other major component of a microbial
backstop would be provisions for disinfection profiling and
benchmarking, which are discussed in Section D. of this Notice.
The revisions to the turbidity provisions (including the individual
filter provisions) recommended by the Committee would also contribute
to the microbial backstop objective in direct relationship to the
treatment process itself. The reliability of the disinfection barrier
as a means for preventing waterborne disease should increase
substantially as a result of these tighter turbidity provisions
because:
--There would be fewer and shorter periods of elevated turbidity during
which the disinfection barrier could be compromised; and
--The removal of particulate matter achieved by the filtration process
will both be higher on average and more consistent throughout the
treatment cycle, thus putting less burden on the disinfection barrier.
a. 95th Percentile and Maximum Turbidity Levels of Composite
Filtered Water.
Three data sets, summarizing the historical turbidity performance
of various filtration plants, were evaluated to assess the national
impact of modifying existing turbidity requirements. This included
turbidity information from the American Water Works Service Company
(AWWSC, 1997), a multi-State data set (which was analyzed in two sets)
(SAIC, 1997), and information from plants participating in the
Partnership for Safe Water program (Bissonette, 1997). Only turbidity
data from plants serving populations greater than 10,000 persons were
used. The analyses also included only plants that met the current 95th
percentile turbidity standard, 0.5 NTU, and the current maximum
turbidity standard, 5 NTU, in all months. Each of the data sets was
analyzed to assess the current performance of plants with respect to
the number of months in which selected 95th percentile and maximum
turbidity levels were exceeded.
The AWWSC is a privately-held company that owns and operates for
profit about 70 water treatment facilities located across the country.
For this analysis, the AWWSC data set (AWWSC, 1997) included one year's
data for 45 plants in 10 States. The States, with number of plants in
each state listed in parentheses, are as follows: California (1),
Connecticut (3), Iowa (2), Indiana (6), Maryland (1), Missouri (2),
Pennsylvania (24), Tennessee (1), Virginia (2), and West Virginia (3).
USEPA analyzed the composite filtered effluent turbidity data obtained
from the AWWSC plants measured every 4-hours.
The analyses examined two variations of turbidity data obtained
from the multi-State data set (SAIC, 1997). The multi-State data set
included 86 plants in 11 states. The States, with number of plants in
each state listed in parentheses, are as follows: California (10),
Georgia (5), Kansas (9), New Jersey (5), Ohio (12), Oregon (10), Rhode
Island (6), Texas (9), Wisconsin (8), West Virginia (6), Wyoming (6).
The State data was analyzed as two data sets, denoted as State 1 and
State 2. The State 1 data set included only plant information with
measurements every 4 hours, comprising slightly more than half of the
State data (47 plants in CA (10), OR (10), TX (9), WI (6), WY (6), WV
(6)). The State 2 data set was comprised of both the State 1 data and
other data including plant information consisting of daily maximum
turbidity values only, altogether 86 plants.
The State 1 data set was expected to provide a more accurate
picture of typical plant performance among the plants in the entire
State data set because there were more data points per plant. However,
the State 2 data set increased regional coverage by incorporating data
from five additional States (GA, KS, NJ, OH, RI) to reflect additional
geographic variation that may not have been captured in the State 1
data set.
In order to determine how many of the systems met lower 95th
percentile turbidity levels based on turbidity measurements every four
hours, the data from those States in which systems only report maximum
daily values had to be statistically adjusted. The adjustment is
necessary to take into account the difference in the number of reported
measurements in a month that can exceed a particular level (e.g., 0.3
NTU) without exceeding the monthly 95th percentile for that level.
(Systems that report measurements every four hours can have up to 9 of
180 measurements (5%) that exceed the level in a month; however, there
is no way to directly calculate an equivalent value for systems that
only report daily maximum values without making some adjustment.) No
adjustment was necessary for assessing monthly maximum turbidity
levels.
The State 2 analyses adjusted the monthly 95th percentile turbidity
levels for plants with only daily maximum data. This was done because
the 95th percentile based on 31 daily turbidity maximums a month will
overestimate the 95th percentile based on 186 daily measures (or
measurements every 4 hours). To assess the magnitude of the bias, the
State 1 data were used to examine the relationship between the 95th
percentile of the daily maximums and the 95th percentile of the daily
measurements.
The State 2 monthly 95th percentile analyses were obtained by
dividing the estimated monthly 95th percentiles of those systems
reporting only daily maximums by a factor of 1.2 to account for bias.
This factor was derived as follows. The daily maximum was determined
for each day in the State 1 data set and a monthly 95th percentile (of
the 30 or 31 daily maximums) was determined, i.e., the second largest
daily maximum. The corresponding monthly 95th percentile based on the
daily data was also determined. The ratio of these two values was then
calculated and summarized across months. The median ratio across all
months was 1.2, with 90 percent of the ratios ranging between 1.0 and
1.9. The analysis used to derive the adjustment factor examined only
plants that reported six values per day.
The remaining data set included in the turbidity analysis was of
plants participating in the Partnership for Safe Water. The Partnership
for Safe Water is a joint venture of several organizations, including
the American Water Works Association, the Association of State Drinking
Water Administrators, the Association of Metropolitan Water Agencies,
the National Association of Water Companies, the American Water Works
Association Research Foundation and USEPA. These organizations
[[Page 59500]]
entered into a voluntary ``partnership'' with the nation's drinking
water filtration plants treating surface water to tighten treatment
practices and operational controls to reduce the risk from
Cryptosporidium and other waterborne pathogens. The Partnership
approach, described in the ``Partnership for Safe Water Voluntary Water
Treatment Plant Performance Improvement Program Self-Assessment
Procedures'' (USEPA et al. 1995), is based on USEPA's Composite
Correction Program (CCP). The CCP is a voluntary program which is
described in detail in the handbook Optimizing Water Treatment Plant
Performance Using the Composite Correction Program--USEPA/625/6-91/027.
The Partnership for Safe Water utility membership consists of 199
utilities representing almost 280 water treatment plants. These plants
serve approximately 80 million persons. The Partnership consists of
four phases with each phase providing tools and methodologies to assist
utilities in progressing toward a higher quality finished water. The
following data summarizes turbidity performance based on 4-hour
measurements reported by the Partnership utilities for 12 months
overlapping 1995 and 1996. The data represents a composite of
Partnership utilities that have completed varying phases of Partnership
activities, ranging from having just joined to having progressed well
into the self-assessment phase (phase 3). All data were derived from
the 1997 Partnership for Safe Water Annual report (Bissonette, 1997).
The results of the analyses of all of the data sets are shown in
Tables 3 and 4.
Tables 3 and 4 indicate the extent to which plants, as currently
operated, are meeting different turbidity levels. Conversely the data
indicate the portion of utilities which might need to alter existing
practice in order to meet lower turbidity limits, if such limits were
required through regulation.
Table 3 is organized to reflect the extent to which utilities are
currently meeting monthly 95th percentile turbidity limits, assuming
that compliance with such limits is determined as currently done under
the existing monthly 95th percentile standard of < 0.5="" ntu.="" for="" example,="" table="" 3="" indicates="" that="" 19.1="" percent="" (based="" on="" the="" partnership="" data="" set)="" and="" 34.9="" percent="" (based="" on="" the="" state="" 2="" data="" set)="" exceed="" a="" monthly="" 95th="" percentile="" turbidity="" limit="" of="" 0.3="" ntu="" at="" least="" one="" month="" during="" the="" year="" for="" which="" data="" were="" collected.="" table="" 3="" also="" indicates="" the="" extent="" to="" which="" utilities="" meet="" a="" particular="" limit="" for="" multiple="" months="" of="" the="" year="" (i.e.,="" for="" at="" least="" 3="" months="" and="" for="" at="" least="" 6="" months).="" the="" frequency="" in="" months="" by="" which="" utilities="" exceed="" a="" particular="" monthly="" turbidity="" limit="" could="" influence="" the="" extent="" of="" treatment="" that="" might="" be="" needed="" to="" achieve="" compliance="" through="" out="" the="" year.="" the="" technical="" work="" group="" (twg)="" which="" provided="" technical="" advice="" to="" the="" advisory="" committee="" made="" the="" following="" recommendations="" for="" estimating="" national="" compliance="" forecasts.="" (1)="" the="" state="" 2="" data="" set="" could="" be="" used="" as="" a="" reference="" point="" for="" estimating="" potential="" compliance="" burdens="" for="" systems="" serving="" less="" than="" 100,000="" people.="" the="" partnership="" data="" could="" be="" used="" as="" a="" reference="" point="" for="" estimating="" potential="" compliance="" burdens="" for="" systems="" serving="" greater="" than="" 500,000="" people.="" for="" systems="" serving="" between="" 100,000="" and="" 500,000="" people,="" the="" average="" of="" the="" percentages="" of="" systems="" not="" meeting="" a="" particular="" limit="" reflected="" by="" the="" partnership="" and="" state="" 2="" data="" could="" be="" used="" for="" estimating="" compliance="" burdens.="" (2)="" estimates="" for="" systems="" needing="" to="" make="" changes="" to="" meet="" a="" turbidity="" performance="" limit="" of="">< 0.3="" ntu="" should="" be="" based="" on="" the="" ability="" of="" systems="" currently="" being="" able="" to="" meet="" a="" 0.2="" ntu="" as="" reflected="" in="" table="" 3.="" this="" assumption="" would="" also="" take="" into="" account="" a="" utility's="" concern="" with="" possible="" turbidity="" measurement="" error.="" for="" example,="" for="" systems="" serving="" less="" than="" 100,000="" people,="" the="" twg="" assumed="" that="" 51.7="" percent="" of="" the="" systems="" could="" be="" expected="" to="" make="" treatment="" changes="" to="" consistently="" comply="" with="" a="" monthly="" 95th="" percentile="" limit="" of="" 0.3="" ntu.="" similarly,="" for="" systems="" serving="" over="" 500,000="" people,="" the="" twg="" assumed="" that="" 41.7="" percent="" could="" be="" expected="" to="" make="" treatment="" changes="" to="" comply="" with="" a="" 0.3="" ntu="" regulatory="" limit.="" table="" 4="" is="" organized="" to="" reflect="" the="" extent="" to="" which="" utilities="" meet="" different="" monthly="" maximum="" turbidity="" limits="" (i.e.,="" all="" measurements="" taken="" during="" the="" month="" must="" be="" below="" the="" indicated="" limit).="" for="" example,="" table="" 4="" indicates="" that="" 6="" percent="" of="" the="" plants="" (based="" on="" state="" 2="" partnership="" data)="" are="" currently="" exceeding="" a="" monthly="" maximum="" limit="" of="" 1.0.="" the="" data="" in="" table="" 4="" were="" considered="" for="" evaluating="" possible="" national="" impacts="" of="" lowering="" the="" current="" maximum="" limit="" of="" 5="" ntu="" to="" some="" lower="" value.="" regarding="" maximum="" turbidity="" levels,="" the="" advisory="" committee="" also="" discussed="" filtered="" water="" turbidity="" levels="" with="" respect="" to="" the="" cryptosporidiosis="" outbreak="" in="" milwaukee="" in="" 1993.="" some="" members="" indicated="" concern="" that="" filtered="" water="" turbidities="" associated="" with="" the="" outbreak="" apparently="" were="" significantly="" lower="" than="" the="" current="" maximum="" turbidity="" level="" of="" 5="" ntu.="" indications="" are="" that="" the="" turbidity="" levels="" were="" at="" about="" 2="" ntu="" (mackenzie="" et="" al.,="" 1994;="" fox="" and="" lytle.,="" 1996).="" table="" 3.--number="" and="" percent="" of="" plants="" that="" exceeded="" monthly="" 95th="" percentile="" turbidity="" limits="" in="" at="" least="" n="" months="" out="" of="" 12="" ----------------------------------------------------------------------------------------------------------------="" at="" least="" 1="" month="" at="" least="" 3="" months="" at="" least="" 6="" months="" turbidity="" limit="" data="" source="" -----------------------------------------------------------------="" num="" pct="" num="" pct="" num="" pct="" ----------------------------------------------------------------------------------------------------------------="" 0.1..........................="" state="" 1........="" 34="" 72.3="" 28="" 59.6="" 24="" 51.1="" state="" 2="" 69.............="" 80.2="" 59="" 68.6="" 51="" 59.3="" awwsc="" 33.............="" 73.3="" 24="" 53.3="" 15="" 33.3="" partnership="" 177............="" 75.3="" 136="" 57.9="" 100="" 42.6="" 0.2..........................="" state="" 1........="" 17="" 36.2="" 9="" 19.1="" 2="" 4.3="" state="" 2="" 44.............="" 51.2="" 29="" 33.7="" 15="" 17.4="" awwsc="" 12.............="" 26.7="" 7="" 15.6="" 2="" 4.4="" partnership="" 98.............="" 41.7="" 51="" 21.7="" 27="" 11.5="" 0.3..........................="" state="" 1........="" 10="" 21.3="" 3="" 6.4="" 0="" 0.0="" state="" 2="" 30.............="" 34.9="" 11="" 12.8="" 3="" 3.5="" awwsc="" 6..............="" 13.3="" 1="" 2.4="" 0="" 0.0="" partnership="" 45.............="" 19.1="" 17="" 7.2="" 7="" 3.0="" 0.4..........................="" state="" 1........="" 3="" 6.4="" 0="" 0.0="" 0="" 0.0="" state="" 2="" 9..............="" 10.5="" 1="" 1.2="" 0="" 0.0="" awwsc="" 3..............="" 6.7="" 0="" 0.0="" 0="" 0.0="" [[page="" 59501]]="" partnership="" 22.............="" 9.4="" 5="" 2.1="" 3="" 1.3="" ----------------------------------------------------------------------------------------------------------------="" population="" served="">10,000. State 1 (4-hour daily data from 47 plants): 10 CA, 10 OR, 9 TX, 6 WI, 6 WV,
6 WY. State 2 (86 plants including State 1 data and daily maximums * from additional plants) : 10 CA, 5 GA, 9
KS, 5 NJ, 12 OH, 10 OR, 6 RI, 9 TX, 8 WI, 6 WV, 6 WY. AWWSC: 45 plants: 1 CA, 3 CT, 2 IA, 6 IN, 1 MD, 2 MO, 24
PA, 1 TN, 2 VA, 3 WV. Partnership for Safe Water 235 plants. *For plants with only daily maximums, the monthly
95th percentile was estimated as the 95th percentile of the daily maximums divided by 1.2. The adjustment was
done to account for the potential bias of taking the 95th percentile of daily maximums, and was based on the
relationship observed in the State 1 data between the 95th percentile of the daily maximums and the 95th
percentile of the 4-hour data.
Table 4.--Number and Percent of Plants That Exceeded Monthly Maximum Turbidity Limits in at Least N Months out
of 12
----------------------------------------------------------------------------------------------------------------
At least 1 month At least 3 months At least 6 months
Maximum turbidity limit Data source -----------------------------------------------------------------
Num Pct Num Pct Num Pct
----------------------------------------------------------------------------------------------------------------
0.3.......................... State 1........ 36 76.6 15 31.9 6 12.8
State 2 69............. 80.2 36 41.9 15 7.4
AWWSC 24............. 53.3 10 22.2 4 8.9
Partnership 129............ 54.9 72 30.6 37 15.7
0.5.......................... State 1........ 18 38.3 3 6.4 1 2.1
State 2 35............. 40.7 7 8.1 1 1.2
AWWSC 12............. 26.7 3 6.7 0 0.0
Partnership 65............. 27.7 20 8.5 5 2.1
1.0.......................... State 1........ 1 2.1 0 0.0 0 0.0
State 2 6.............. 7.0 0 0.0 0 0.0
AWWSC 4.............. 8.9 0 0.0 0 0.0
Partnership 16............. 6.8 4 1.7 2 0.9
2.0.......................... State 1........ 1 2.1 0 0.0 0 0.0
State 2 2.............. 2.3 0 0.0 0 0.0
AWWSC 0.............. 0.0 0 0.0 0 0.0
Partnership 7.............. 3.0 2 0.9 1 0.4
----------------------------------------------------------------------------------------------------------------
b. Individual Filter Performance.
During a turbidity spike, significant amounts of particulate matter
(including oocysts, if present) may pass through the filter. Figure 3
presents the turbidity levels over time of a typical filter. The
greatest potential for a peak (and thus, pathogen break-through) is
near the beginning of the filter run after filtered backwash or start
up of operation (Amirtharajah 1988; Bucklin et al. 1988; Cleasby 1990;
and Hall and Croll 1996).
Various factors effect the duration and amplitude of filter spikes,
including sudden changes to the flow rate through the filter, treatment
of the filter backwash water, filter to waste capability, and site-
specific water quality conditions. The M-DBP Advisory Committee also
discussed the need to control turbidity spikes in order to limit the
number of oocysts passing through the filter.
BILLING CODE 6560-50-P
[[Page 59502]]
[GRAPHIC] [TIFF OMITTED] TP03NO97.045
BILLING CODE 6560-50-C
c. Turbidity Measurement.
Turbidity is a measure of light scatter that is affected by the
size distribution and shape of suspended particles in the water. Four
methods are commonly used to measure turbidity and all are approved for
use under the SWTR. They include the Nephelometric Method listed in
2130B of the Standard Methods for the Examination of Water and
Wastewater, Standard Test Method for Turbidity of Water ASTM (1990)
D1889-94, the Nephelometric Method in 180.1 of USEPA-600/R-93-100 and
the Great Lakes Instruments Method 2 (see section 141.74(a)(1)).
Turbidimeters which measure turbidity commonly consist of the
following components: (1) a light source and lenses and other optical
devices to project the light beam at the sample container and to direct
the scattered light to the detector; (2) a transparent cell that
contains the water to be measured; (3) light traps within the sample
chamber that minimize the amount of stray light that reaches the
detector; and (4) a meter that indicates the intensity of the light
reaching the detector. While turbidity measurement has long been
recognized as a means for evaluating treatment performance for removal
of particulate matter (which include microorganisms), issues remain
pertinent to the accuracy and precision of the measurement (Hart et al.
1992; Sethi et al. 1997).
Large tolerances in instrument design criteria, intended to promote
competition among instrument manufacturers, have lead to turbidimeters
with significantly different design features being available on the
market. Turbidimeters with different designs (but within the design
specifications of Standard Methods), calibrated according to
manufacturer's recommendations, have been shown to provide different
turbidity readings for a given suspension (Hart et al. 1992). The
significance of this phenomenon as it might pertain to the same water
with changing turbidities over time or different waters in the U.S. is
not known. Therefore, narrowing instrument design criteria could reduce
variation of turbidity measurement but the best direction that such
change should take is not yet apparent.
Calibration procedures also affect turbidity measurements.
Calibration typically involves placing a quantity of a standard
suspension in the turbidimeter and then adjusting the response so that
the meter gives a reading equal to the turbidity value assigned to the
standard. Instruments that are calibrated with currently approved
different standard suspensions can yield different turbidity
measurements on the same water (Hart et al. 1992). The significance of
this phenomenon as it might pertain to the same water with changing
turbidities over time or different waters in the U.S. is also not
known. While narrowing specifications for current calibration
procedures could reduce variation of turbidity measurements, the best
direction that such change should take is not yet apparent.
Other factors that may affect turbidity measurement include
procedures used to prepare and wipe the sample cell and use of sample
degassing procedures. The extent to which all of the above factors,
collectively, affect turbidity measurement is not known. However, past
performance evaluation (PE) studies conducted by USEPA provide some
indication of accuracy and precision of turbidity measurements among
different laboratories for a common synthetically prepared water. In PE
studies, PE samples with known turbidity levels are sent to
participating laboratories (who are not informed of the turbidity
level). Laboratories participating in these studies used turbidimeters
from various manufacturers and conducted their analysis in accordance
with calibration and analytical procedures they are familiar with.
Thus, the variability of the results reflect differences resulting from
using different turbidimeter models and methods and the effects of
different laboratory procedures. Table 5 summarizes results from PE
studies conducted at turbidity levels close to the SWTR turbidity
performance limit of 0.5 NTU. The Relative Standard Deviation (RSD) is
the Standard Deviation divided by the mean. It appears that the RSD at
turbidity levels considered in these PE studies are slightly below 20%.
(A RSD of 20% implies that 95% of one-time turbidity measurements made
by different laboratories would fall within 40% of the mean. The RSD
for an individual laboratory, making numerous measurements on a given
sample water would be expected to be significantly less than that
achieved among different laboratories (using a variety of turbidimeters
as indicated in Table 5).
[[Page 59503]]
Table 5.--USEPA Performance Evaluation Results of Turbidity Measurements (USEPA 1997d)
[Turbidity readings are expressed in NTU, and Relative Standard Deviation in %]
----------------------------------------------------------------------------------------------------------------
No. of Relative S
Study No. True Turb. samples Mean D
----------------------------------------------------------------------------------------------------------------
34 USEPA/State............................................. .720 54 .752 16.0
34 All Lab................................................. .720 1503 .744 15.8
23 USEPA/State............................................. .650 24 .659 10.1
25 USEPA/State............................................. .600 28 .585 13.8
25 All Lab................................................. .600 708 .597 16.0
25 USEPA/State............................................. .450 29 .463 20.5
25 All Lab................................................. .450 707 .481 19.5
22 USEPA/State............................................. .350 52 .406 16.1
----------------------------------------------------------------------------------------------------------------
No data is yet available on measurement performance from PE studies
at levels less than 0.3 NTU. A major concern expressed by participants
among the Advisory Committee is the ability to reliably measure low
turbidity levels. The TWG assumed that if systems operated to achieve a
turbidity limit of less than 0.2 NTU 95 percent of the time, this would
provide an adequate margin of safety from variability in treatment
performance and turbidity measurement error, to consistently meet a
turbidity limit of 0.3 NTU.
USEPA intends to conduct two PE studies with true turbidities
ranging from 0.1 to 0.3 NTU. One study is planned to begin no later
than the end of January 1998 and the other study within 6 months
thereafter. These new studies will provide an indication of accuracy
and precision of turbidity measurements at lower levels than previously
examined. Measurements by on-line turbidimeters will also be evaluated.
On-line monitoring issues: For expedience, on-line turbidimeters
are often calibrated against a bench instrument that has been
accurately calibrated by comparing the turbidity level in a water
sample. However, at regular intervals they need to be taken off line
and calibrated, as for bench instruments, by pouring the prepared
standard suspension into the chamber of the instrument. On-line
instruments must be inspected regularly to remove air bubbles and
accumulated debris. Fluctuations in continuous measurements do not
necessarily signify a decrease in water treatment performance.
Fluctuations in continuous measurements should be investigated since
they may be due to air bubbles, debris or a temporary disturbance due
to a change in the flow rate of sample water flow through the
turbidimeter. To address the contingency of such phenomenon, the
Advisory Committee recommended, based on advice from the Technical Work
Group, that turbidity spikes should be defined on the basis of at least
2 consecutive measurements taken over some interval of time (e.g., 15
minutes).
There is no standard design specification for on-line turbidimeters
regarding chamber size and recommended flow rate. Thus, turbidity
spikes of the treated water will be reflected with a delay of a few
seconds to a few minutes, depending on chamber volume and flow rate of
the turbidimeter. A turbidity peak measured by a turbidimeter with a
large chamber volume and small flow rate will result in slightly
reduced peak.
3. Advisory Committee Recommendations and Related Issues
USEPA reiterates its request for comment on the following
recommendations of the M-DBP Advisory Committee.
1. Turbidity Performance Requirements. For all surface water
systems that use conventional treatment or direct filtration, serve
more than 10,000 people, and are required to filter: (a) the
turbidity level of a system's combined filtered water at each plant
must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month and, (b) the turbidity level of a
system's combined filtered water at each plant must at no time
exceed 1 NTU. For both the maximum and the 95th percentile
requirements, compliance shall be determined based on measurements
of the combined filter effluent at four-hour intervals.
2. Individual Filter Requirements. All surface water systems
that use rapid granular filtration, serve more than 10,000 people,
and are required to filter shall conduct continuous monitoring of
turbidity for each individual filter and shall provide an exceptions
report to the State on a monthly basis. Exceptions reporting shall
include the following: (1) any individual filter with a turbidity
level greater than 1.0 NTU based on 2 consecutive measurements
fifteen minutes apart; and (2) any individual filter with a
turbidity level greater than 0.5 NTU at the end of the first 4 hours
of filter operation based on 2 consecutive measurements fifteen
minutes apart. A filter profile will be produced if no obvious
reason for the abnormal filter performance can be identified.
If an individual filter has turbidity levels greater than 1.0
NTU based on 2 consecutive measurements fifteen minutes apart at any
time in each of 3 consecutive months, the system shall conduct a
self-assessment of the filter utilizing as guidance relevant
portions of guidance issued by the Environmental Protection Agency
for Comprehensive Performance Evaluation (CPE). If an individual
filter has turbidity levels greater than 2.0 NTU based on 2
consecutive measurements fifteen minutes apart at any time in each
of two consecutive months, the system will arrange for the conduct
of a CPE by the State or a third party approved by the State.
3. State Authority: States must have rules or other authority to
require systems to conduct a Composite Correction Program (CCP) and
to assure that systems implement any follow-up recommendations that
result as part of the CCP.
In reference to the above recommendations, EPA also requests
comment on what would or would not constitute an obvious reason for
abnormal filter performance. The Agency also requests comment on how
much time a system should have to conduct a self-assessment of the
filter and how much time a system should have to arrange for the
conduct of a CPE under circumstances such as described in the
recommendations.
USEPA also requests comment on whether there are particular filters
currently in operation in the United States for which specific guidance
may be needed with regard to individual filter monitoring. For example,
some members of the M-DBP Advisory Committee suggested that special
guidance be developed for unique filtration devices made by Infilco
Degremeont (previously made by Aldridge). These devices consist of
multi-celled filters with a traveling bridge-automated back washing
unit that are not conducive to individual cell monitoring.
USEPA also requests comment regarding existing SWTR provisions for
lime softening plants that have very low
[[Page 59504]]
turbidity in source waters. The existing SWTR allows States to set
numerically higher standards up to 1 NTU in 95 percent of samples taken
per month for conventional treatment and direct filtration plants if
the State determines that on-site studies demonstrate at least 99.9
percent overall removal and/or inactivation of Giardia cysts. (54 FR
27503). In the SWTR (54 FR 27486), the Agency notes that actual
demonstrations ``(e.g. with pilot plant study results)'' are not
required for the State to determine when minimum performance
requirements at the higher turbidity level might be appropriate for a
particular system. The SWTR states:
Instead, the State's determination may be based upon an analysis
of existing design and operating conditions (e.g. adequacy of
treatment prior to filtration, percent turbidity removal across the
entire treatment train, stringency of disinfection) and/or
performance relative to certain water quality characteristics (e.g.
microbiological analysis of the filtered water, particle size counts
in water before and after filtration). The State may wish to
consider such factors as source water quality and system size in
determining the extent of analysis necessary. (54 FR 27503).
Committee members raised situations where filtration plants have
been designed for specific source water quality characteristics such as
high alkalinity and extremely low turbidity water (e.g. 0.1 to 0.5
NTU). In systems with such source waters, turbidity levels from the
filters may actually be higher than in the source waters due to
reactions from chemicals added mainly for purposes other than source
water particle removal. Lime softening plants operating under certain
conditions, depending upon process configuration and raw water
characteristics or when flocculation conditions change, may
periodically experience a carry over of extremely fine calcium
carbonate or magnesium hydroxide particles. These fine particles may
pass through filters thereby resulting in artificially elevated
effluent turbidity levels. If turbidity performance criteria are
tightened under the IESWTR some plants may have difficulty meeting
these criteria but still achieve substantial removal of Giardia
lamblia, Cryptosporidium parvum, and viruses. As reflected in the 1989
SWTR, USEPA believes that in cases where lime softening is practiced
and source water turbidity levels are low, provisions for alternative
treatment performance criteria (i.e., in lieu of turbidity) may be
appropriate.
As in the present SWTR, USEPA believes that demonstrations of
equivalent protection need not be based on actual demonstrations (e.g.
pilot plant study results). Instead the State's determination can be
based on the factors cited at 54 FR 27503 as quoted above. Other
factors related to source water microbial quality (e.g. pristine source
water, source water protection programs, microbial monitoring results,
bank filtration) may be appropriate for such determinations.
USEPA requests comment on the appropriateness of continuing
existing provisions that provide States the flexibility of approving
higher turbidity levels up to 1 NTU in 95 percent of samples per month
and up to 2 NTU maximum turbidity for such plants, and additionally
seeks comments on:
What types of plants might fall in this category (e.g.
softening plants designed for color and hardness removal with very
low turbidity source waters);
What demonstrations of equivalent protection from
Giardia lamblia, Cryptosporidium parvum, and viruses are appropriate
(e.g. microbiological analysis of the filtered water, monitoring
results for protozoans, watershed control, wellhead protection
programs);
What additional or alternative requirements States
might place on such systems to insure the objective of equivalent
protection from Giardia lamblia, Cryptosporidium parvum, and viruses
(e.g. regular monitoring for protozoans in source and or filtered
water, or for other water quality parameters, watershed control,
well head protection programs);
Allowing systems to acidify turbidity samples when
calcium carbonate carry-over exists to obtain true turbidity
readings; and
The appropriateness of including source water microbial
quality measurements or surrogates as part of a State determination
of equivalent protection when considering whether to authorize
higher operating turbidity levels.
D. Disinfection Benchmark for Stage 1 DBP MCLS
A fundamental principle of the 1992-93 regulatory negotiation which
was reflected in the 1994 proposal for the IESWTR was that new
standards for control of byproducts must not result in significant
increases in microbial risk. This principle was also one of the
underlying premises of the M-DBP Advisory Committee's deliberations,
i.e., that existing microbial protection must not be significantly
reduced or undercut as a result of systems taking the necessary steps
to comply with the Stage 1 DBPR. The Advisory Committee's
recommendations to meet this key objective are discussed in this
section.
The approach outlined below represents the recommendation of the
Advisory Committee to develop a mechanism that is designed to assure
that pathogen control is maintained while the Stage 1 DBPR provisions
are implemented. Briefly, the disinfection benchmark addresses the
three issues of who must gather the necessary information to evaluate
current practices, how the benchmark operates, and finally, how the
system and the State work together to assure that microbial control is
maintained.
Based on data provided by systems and reviewed by the TWG, the
baseline of microbial inactivation (expressed as logs of Giardia
lamblia inactivation) demonstrated high variability. Inactivation
varied by several logs on a day-to-day basis at any particular
treatment plant and by as much as tens of logs over a year due to
changes in water temperature, flow rate (and consequently contact
time), seasonal changes in residual disinfectant, pH, and disinfectant
demand (and consequently disinfectant residual). There were also
differences between years at individual plants.
To address these variations, the TWG developed an approach for a
system to use to characterize disinfection practice; the procedure is
called profiling. In essence, this approach allows a plant to chart or
plot its daily levels of Giardia inactivation on a graph which, when
viewed on a seasonal or annual basis, represents a ``profile'' of the
plant's inactivation performance. The system can use the profile to
develop a baseline or benchmark of inactivation against which to
measure possible changes in disinfection practice. This approach makes
it possible for a plant that may need to change practice to meet DBP
MCLs to assure no significant increase in microbial risk. It provides
the necessary tool to allow plants to project or measure the possible
impacts of potential changes in disinfection. Only certain systems
would be required to develop a profile and keep it on file for State
review during sanitary surveys, and only a subset of those required to
develop a profile would be required to submit it to the State as part
of a package submitted when the system is making significant changes to
its disinfection practice.
USEPA reiterates its request for comment on the following
recommendations of the M-DBP Advisory Committee that address the three
questions outlined above: (1) who should develop a profile, (2) how a
profile is actually generated, and (3) how the profile will be used.
1. Applicability
Systems would be required to prepare a disinfection profile, if at
least one of the following criteria are met:
[[Page 59505]]
(1) TTHM levels are at least 80% of the MCL (0.064 mg/l) as an
annual average for the most recent 12 month compliance period for
which compliance data are available prior to November 1998 (or some
other period designated by the State). Monitoring would be in
accordance with current TTHM requirements.
(2) Haloacetic acid (HAA5) levels are at least 80% of the MCL
(0.048 mg/l) as an annual average for the most recent 12 month
period for which data are available (or some other period designated
by the State). In connection with HAA5 monitoring, the following
provisions apply:
(a) Systems that have collected HAA5 data under the ICR must use
those data to determine the HAA5 level, unless the State determines
that there is a more representative annual data set.
(b) If the system does not have four quarters of HAA5 data by
the end of 90 days following the IESWTR promulgation date, the PWS
must conduct HAA5 monitoring for four quarters. This monitoring must
comply with the monitoring requirements included in the DBP Stage 1
rule.
(The Advisory Committee recommended a value of 80% of the MCL
because available data indicated that DBP levels varied from year to
year due to many factors (e.g., changes in source water quality,
changes in water demand). The Committee believed that targeting a level
20% below the MCL would include most systems that would be expected to
make changes to comply with the TTHM and HAA5 MCLs on a continuing
basis. Also, USEPA previously considered this target level at the
recommendation of the 1992 reg-neg committee, to evaluate DBP Stage 1
compliance forecasts and costs, based upon the judgement that most
facilities will take additional steps to ensure continuing MCL
compliance if they are at or above these levels.)
2. Developing the Profile and Benchmark
As outlined above, profiling is the characterization of a system's
disinfection practice over a period of time. The system can create the
profile by conducting new daily monitoring or by using
``grandfathered'' data (as explained below). A disinfection profile
consists of a compilation of daily Giardia lamblia log inactivations
(or virus inactivations under conditions to be specified in the final
rule), computed over the period of a year, based on daily measurements
of operational data (disinfectant residual concentration(s), contact
time(s), temperature(s), and where necessary, pH(s)).
Grandfathered data are those operational data that a system
previously collected at a treatment plant during the course of normal
operation. These data may or may not have been used previously for
compliance determinations with the SWTR. Those systems that have all
necessary data to determine profiles, using operational data collected
prior to promulgation of the IESWTR, would be able to use up to three
years of operational data in developing profiles. Grandfathered
operational data should be substantially equivalent to operational data
that would be collected under this rule.
Those systems that do not have three years of operational data to
develop profiles would have to conduct monitoring to develop the
profile for one year beginning no later than 15 months after IESWTR
promulgation. If the PWS has existing operational data to develop
profiles, it would have to use those data to develop profiles for the
years prior to the IESWTR promulgation.
In order to develop the profile, a system would have to:
--Measure disinfectant residual concentration (C, in mg/l) prior to
entrance into distribution system and just prior to each additional
point of disinfectant addition, whether with the same or a different
disinfectant.
--Determine contact time (T, in minutes) during peak flow conditions. T
can be based on either a tracer study or assumptions based on contactor
geometry and baffling. However, systems would have to use the same
method for both grandfathered data and new data.
--Measure water temperature ( deg. C).
--Measure pH (for chlorine only).
The system would then have to convert operational data to log
inactivation values for Giardia (and viruses when chloramines or ozone
used as primary disinfectant).
--Determine CTactual for each disinfection segment.
--Determine CT99.9 (i.e., 3-logs inactivation) from tables
in the SWTR/IESWTR using temperature (and pH for chlorine) for each
disinfection segment. [NOTE: USEPA may redesign the tables so that no
conversion is necessary (i.e., the tables will reflect a
CT90 (1-log) value.]
--For each segment, log inactivation = (CTact/
CT99.9) x 3.0.
A log inactivation benchmark would then be calculated as follows:
1. Calculate the average log inactivation for each calendar month.
2. Determine the calendar month with the lowest average log
inactivation.
3. The lowest average month becomes the critical period for that
year.
4. If data from multiple years are available, the average of
critical periods for each year becomes the benchmark.
5. If only one year of data is available, the critical period for
that year is the benchmark.
3. State Review
The State would review disinfection profiles as part of its
periodic sanitary survey. If a system that is required to develop a
disinfection profile subsequently decides to make a significant change
in disinfection practice, it would have to consult with the State
before implementing such a change. Significant changes would be defined
as: (1) moving the point of disinfection, (2) changing the type of
disinfectant, (3) changing the disinfection process, or (4) making any
other change designated as significant by the State. Supporting
materials for such consultation would have to include a description of
the proposed change, the disinfection profile, and an analysis of how
the proposed change will affect the current disinfection benchmark.
4. Guidance
USEPA, in consultation with interested stakeholders, will develop
guidance for States and systems on how to develop and evaluate
disinfection profiles, how to identify and evaluate significant changes
in disinfection practices, and guidance on moving the point of
disinfection from before the point of coagulant addition to after the
point of coagulant addition. USEPA will also develop guidance for
systems that would be required to develop a profile based on virus
inactivation instead of Giardia lamblia inactivation. Guidance will be
available when the IESWTR is promulgated.
5. Request for Public Comment
USEPA requests comment on all aspects of the recommendation
outlined above and any alternative suggestions that stakeholders or
other interested parties may have. Commenters may want to focus
particular attention on the following issues:
--Applicability requirements,
--Characterization of disinfection practices and components (e.g.,
monitoring, analysis),
--Use of TTHM and HAA5 data from the same time period instead of TTHM
data from one year and HAA5 data from another,
--Definition of significant changes to disinfection practice,
--Different approaches to evaluating possible changes in disinfection
practice against a disinfection profile, and
--Whether the use of grandfathered data, if available, should be
[[Page 59506]]
mandatory for profiling and benchmarking.
E. Definition of Ground Water Under the Direct Influence of Surface
Water (GWUDI)--Inclusion of Cryptosporidium in the Definition
1. Summary of 1994 Proposal and Public Comments
The July 29, 1994, Federal Register notice proposed to amend the
SWTR by including Cryptosporidium in the definition of a GWUDI system.
Under the rule, a system using ground water considered vulnerable to
Cryptosporidium contamination would be subject to the provisions of the
SWTR. USEPA proposed that this determination be made by the State for
individual sources using State-established criteria.
The 1994 proposed IESWTR also requested comment on revisions to
USEPA's guidance on this issue. Cryptosporidium oocysts are smaller
than Giardia cysts and may have substantially different hydrodynamic
behavior in ground water due to their smaller size and perhaps also due
to a difference in charge distribution on the outer surface of the
oocyst. USEPA guidance for the determination of GWUDI suggests methods
that may be insensitive to this differing hydrodynamic behavior in
ground water.
Almost all commenters agreed that Cryptosporidium should be added
to the definition. Only one commenter clearly opposed the addition
without caveat, maintaining that problems with the analytical methods
for the recovery and enumeration of viable organisms and uncertainties
associated with risk assessment should preclude its addition. One
commenter contended that Cryptosporidium should be included only if
USEPA addresses the amount of natural disinfection at each site and
defines treatment effectiveness, especially coagulant use, for GWUDI
systems. One commenter believed that the definition of Cryptosporidium
should be made at the species level, e.g. Cryptosporidium parvum,
because other species were not pathogenic to humans.
One commenter was concerned about the Microscopic Particulate
Analysis (MPA), one of the methods that USEPA identifies in guidance as
being suitable for making GWUDI determinations. As part of this method,
a microscopic examination is made of the ground water to determine
whether insect parts, plant debris, rotifers, nematodes, Giardia
lamblia, and other material associated with the surface or near surface
environment are present. The commenter claimed that the MPA has
analytical method problems similar to those associated with the
recovery of cysts and oocysts from environmental samples and suggested
that the method should undergo additional testing with positive and
negative controls and with performance evaluation samples.
2. Overview of Existing Guidance
USEPA issued guidance on the MPA in October 1992 as the Consensus
Method for Determining Groundwater Under the Direct Influence of
Surface Water Using Microscopic Particulate Analysis. Additional
guidance for making GWUDI determinations is also available (USEPA,
1994e,f). Since 1990, States have acquired substantial experience in
making GWUDI determinations and have documented their approaches
(Massachusetts Department of Environmental Protection, 1993; Maryland,
1993; Sonoma County Water Agency, 1991). Guidance on existing practices
undertaken by States in response to the SWTR may also be found in the
State Sanitary Survey Resource Directory, jointly published in December
1995 by USEPA and the Association of State Drinking Water
Administrators. AWWARF has also published guidance (Wilson et al.,
1996).
3. Summary of New Data and Perspectives
Most recently, Hancock et al. (1997) used the MPA test to study the
occurrence of Giardia and Cryptosporidium in the subsurface. They found
that, in a study of 383 ground water samples, the presence of Giardia
correlated with the presence of Cryptosporidium. The presence of both
pathogens correlated with the amount of sample examined but not with
the month of sampling. There was a correlation between source depth and
occurrence of Giardia but not Cryptosporidium. The investigators also
found no correlation between the distance of the ground water source
from adjacent surface water and the occurrence of either Giardia or
Cryptosporidium. However, they did find a correlation between distance
from a surface water source and generalized MPA risk ratings of high
(high represents an MPA score of 20 or greater), medium or low, but no
correlation was found with the specific numerical values that are
calculated by the MPA scoring system.
USEPA is interested in an expanded discussion of MPA performance.
The work cited here is preliminary information and represents the only
data provided to USEPA so far. USEPA is considering several analytical
activities to address possible changes in the GWUDI determination
guidance. These changes are as follows:
Change the MPA methodology to include a score for
Cryptosporidium oocysts in the risk rating method.
Conduct additional comparison of MPA scores with cyst and
oocyst recovery to evaluate the performance of MPA as an indicator
method (e.g., Schulmeyer, 1995).
Conduct additional MPA performance evaluation testing
(with both positive and negative controls).
Compare MPA scores and cyst/oocyst recovery in horizontal
collector wells and vertical wells to determine if additional guidance
for horizontal collector wells is needed.
4. Request for Public Comment
USEPA is continuing to consider inclusion of Cryptosporidium in the
definition of GWUDI. USEPA requests further comment on this issue as
well as on issues outlined above pertaining to guidance for GWUDI
determinations.
F. Inclusion of Cryptosporidium in Watershed Control Requirements
1. Summary of 1994 Proposal and Public Comments
USEPA proposed to extend the existing watershed control
requirements for unfiltered systems to include the control of
Cryptosporidium. This would be analogous to and build upon the existing
requirements for Giardia lamblia and viruses; Cryptosporidium would be
included in the watershed control provisions wherever Giardia lamblia
is mentioned. USEPA also proposed requiring a State, as a condition of
primacy, to describe how it would judge the adequacy of watershed
control programs for Cryptosporidium as well as Giardia lamblia and
viruses in the source water.
Several commenters to the proposed rule specifically supported
inclusion of Cryptosporidium in watershed control. Others supported
watershed control programs in general without specifically articulating
an opinion on Cryptosporidium. One commenter specifically opposed the
inclusion of Cryptosporidium in watershed control program, maintaining
that other avenues of watershed control could be promoted without
including this organism in the control plan. Another commenter opposed
including Cryptosporidium because environmental sources of Giardia and
Cryptosporidium were not sufficiently understood. This commenter also
opposed the requirement to include Cryptosporidium
[[Page 59507]]
in State watershed control program protocols as a condition of primacy.
Other comments included: (1) Systems need to be informed of the
nature of upstream pathogen sources and changes in upstream water
quality in a timely manner, (2) watershed characteristics should not be
the sole basis for determining water treatment strategies, (3) upstream
sewage discharges should be prohibited and cattle farming and feedlots
prohibited or substantially limited in a watershed, and (4) watershed
control programs should be scientifically based, educational, and
voluntary. One commenter contended that the burden of contamination on
the watershed should not fall to the drinking water systems, and that
better coordination on regulations is needed between the USEPA's
drinking water and wastewater programs.
2. Overview of Existing Guidance
The SWTR specifies the conditions under which a system can avoid
filtration (40 CFR 141.71). These conditions include good source water
quality, as measured by concentrations of coliforms and turbidity,
disinfection requirements; watershed control; periodic on-site
inspections; the absence of waterborne disease outbreaks; and
compliance with the Total Coliform Rule and the MCL for TTHMs.
The watershed control program under the SWTR must minimize the
potential for source water contamination by Giardia lamblia and
viruses. This program must include a characterization of the watershed
hydrology characteristics, land ownership and activities which may have
an adverse effect on source water quality. The SWTR Guidance Manual
(USEPA, 1991a) identifies both natural and human-caused sources of
contamination to be controlled. These sources include wild animal
populations, wastewater treatment plants, grazing animals, feedlots,
and recreational activities. The Guidance Manual recommends that
grazing and sewage discharges not be permitted within the watershed of
unfiltered systems, but indicates that these activities may be
permissible on a case-by-case basis where there is a long detention
time and a high degree of dilution between the point of activity and
the water intake.
3. Summary of New Data and Perspectives
Since proposal of the IESWTR in July 1994, several new outbreaks of
waterborne cryptosporidiosis have occurred in the United States. A
recent summary of these outbreaks (Solo-Gabriele and Neumeister, 1996)
identified raw sewage, surface runoff from livestock grazing areas,
septic tank effluent, cattle wastes, treated wastewater, and backflow
of contaminated water in the distribution system as the suspected
sources of Cryptosporidium contamination of the water supplies in these
outbreaks. Cattle grazing, feedstocks and in particular, calves and
other young livestock, appear to be of greater concern for
Cryptosporidium contamination than for Giardia. Some outbreaks of
cryptosporidiosis have been related to upsets in the treatment process
of filtered water systems or have occurred on occasions when spikes in
turbidity have occurred in those systems. However, little information
is available for unfiltered water systems as to whether spikes in raw
water turbidity increase the likelihood that elevated levels of
Cryptosporidium are present in the source water. Because
Cryptosporidium cannot easily be controlled with conventional
disinfection practices, there is particular concern about the presence
of this organism in the source waters of systems that do not filter.
Data from the ICR may be useful in providing information on the
relative Giardia and Cryptosporidium levels in the raw water sources of
unfiltered and filtered water systems. In one comprehensive study on
Giardia and Cryptosporidium densities in ambient water and drinking
water, investigators (LeChevallier and Norton, 1995) found
Cryptosporidium oocyst levels in ambient water ranging from 0.065/L to
65.1/L, with a geometric mean of 2.4 oocysts/L. In drinking water, the
level of Cryptosporidium oocysts ranged from 0.29-57 oocysts/100L, with
a mean of 3.3 oocysts/100L.
The Seattle Water Department summarized the Giardia and
Cryptosporidium monitoring results from several unfiltered water
systems (Montgomery Watson, 1995). The central tendency of this data is
about 1 oocyst/100L. Thus, depending upon what removal efficiencies are
achieved by filtration for Cryptosporidium (for example, 2 logs), it
appears that unfiltered water systems that comply with the source water
requirements of the SWTR may have a risk of cryptosporidiosis
equivalent to that of a water system with a well-operated filter plant
using a water source of average quality.
Although there are no specific monitoring requirements in the
watershed protection program, the non-filtering utility is required to
develop state-approved techniques to eliminate or minimize the impact
of identified point and non-point sources of pathogenic contamination.
USEPA is considering adding specific monitoring requirements to the
IESWTR for the unfiltered supplies serving 10,000 or more people to
ensure the continued effectiveness of the watershed control program.
The monitoring would be similar to the requirements under the ICR for
Giardia and Cryptosporidium although the sampling frequency may be
modified. As with the ICR, a USEPA-approved method and laboratory for
Giardia and Cryptosporidium analyses would be required.
At a minimum, such a monitoring program might require some level of
routine sampling (e.g., on a weekly, biweekly or monthly basis). The
program may also include ``event'' sampling. An ``event'' would
constitute an occasion when the raw water turbidity and/or fecal/total
coliform concentration exceeded a specific value or possibly exceeded a
site-specific 90th percentile value. At least one sample during an
event might be required in addition to routine sampling. Results of all
protozoa and related analyses would be made available to the State at a
minimum as part of the annual on-site inspection required under the
SWTR for non-filtering supplies.
USEPA is continuing to consider extending the existing watershed
control requirements for unfiltered systems to include the control of
Cryptosporidium. USEPA requests further comment on this issue. The
Agency also requests comment on issues pertaining to monitoring for
unfiltered systems serving 10,000 or more people, including comment on
the following approaches:
Routine Source Water Giardia and Cryptosporidium Monitoring:
Option 1. Weekly Giardia and Cryptosporidium Monitoring
Option 2. Bi-Weekly Giardia and Cryptosporidium Monitoring
Option 3. Monthly Giardia and Cryptosporidium Monitoring
The Agency also requests comments on whether the frequency of
monitoring should depend on system size, e.g., should requirements
differ for systems serving between 10-100,000 people versus those
serving more than 100,000 people.
``Event'' Source Water Giardia and Cryptosporidium Monitoring:
Option 1. No event sampling required.
Option 2. Collect sample(s) for Giardia and Cryptosporidium when
source water turbidity exceeds 1.0 NTU or some alternative value such
as a site-
[[Page 59508]]
specific 90th percentile which might be lower than 1.0 NTU.
Option 3. Collect sample(s) for Giardia and Cryptosporidium when
source water fecal coliform concentration exceeds 20 per 100 mL or
total coliform level exceeds 100 per 100 mL, depending on which class
of coliforms is used under the individual systems filtration avoidance
agreement. Alternatively, the trigger could be some other coliform or
fecal coliform value.
Option 4. Individual utility develops turbidity frequency
distribution (e.g., based on previous 1 to 3 years of daily historical
data) and collects sample(s) for Giardia and Cryptosporidium when
turbidity exceeds 90th percentile level.
Option 5. Some combination of Options 2, 3, or 4.
The Agency also requests comment on whether any of the above
options should depend on system size.
G. Sanitary Survey Requirements
1. Summary of 1994 Proposal and Public Comments
The July 29, 1994, Federal Register proposed to amend the SWTR to
require periodic sanitary surveys for all public water systems that use
surface water, or ground water under the direct influence of surface
water, regardless of whether they filter or not. States would be
required to review the results of each sanitary survey to determine
whether the existing monitoring and treatment practices for that system
are adequate, and if not, what corrective measures are needed to
provide adequate drinking water quality.
The July 1994 notice proposed that only the State or an agent
approved by the State would be able to conduct the required sanitary
survey, except in the unusual case where a State has not yet
implemented this requirement, i.e., the State had neither performed the
required sanitary survey nor generated a list of approved agents. The
proposal suggested that under exceptional circumstances the sanitary
survey could be conducted by the public water system with a report
submitted to the State within 90 days. USEPA also requested comment on
whether sanitary surveys should be required every three or every five
years.
Most commenters on this issue voiced support for requiring a
periodic sanitary survey for all systems. One commenter suggested that
USEPA develop sanitary survey guidance for administration by the
States, while another commenter suggested that sanitary surveys by the
private sector be certified by States or national associations using
USEPA-defined criteria. Commenters recommended that surveys be
conducted either by the State or a private independent party/
contractor. One respondent contended that sanitary surveys, as
presently conducted, were insufficient to assess operational
effectiveness in surface water systems.
With regard to sanitary survey frequency, commenters were nearly
evenly divided between every three years and every five years. Some
commenters argued that the frequency should depend on: (1) whether a
system's control is effective or marginal, (2) system size (less
frequent for small systems), (3) source water quality, (4) whether the
State believes a system's water quality is likely to change over time,
(5) results of the previous survey, and (6) population density on the
watershed. One commenter suggested an annual sanitary survey.
Regarding criteria for sanitary survey inspectors, some commenters
suggested that the State should decide what requirements to use. Others
suggested some combination of education and working experience related
to water plant operations, including (1) professional engineering
certificate and water plant operator license for at least five years,
(2) knowledge of surface water contaminants, source and fate of
contaminants, and both removal capabilities of existing treatment
technologies and ability to evaluate their performance, (3) a BS degree
(preferably MS degree) in sanitary or environmental engineering with
two years experience in evaluating water treatment plants and valid
plant operator's license, (4) five years experience in water system
operation, evaluation, and/or design, and a BS in engineering or
environmental science, (5) a BS degree in science or engineering and
five years experience in the drinking water field.
2. Overview of Existing Regulations and Guidance
Sanitary surveys have historically been conducted by state drinking
water programs as a preventive tool to identify water system
deficiencies that could pose a threat to public health. The first
regulatory requirement for systems to have a periodic on-site sanitary
survey appeared in the final TCR (54 FR 27544-27568). This rule
requires all systems that collect less than 5 total coliform samples
each month to undergo such surveys. These sanitary surveys must be
conducted by the State or an agent approved by the State. Community
water systems were to have had the first sanitary survey conducted by
June 29, 1994, and every five years thereafter while non-community
water systems are to have the first sanitary survey conducted by June
29, 1999, and every five years thereafter unless the system is served
by a protected and disinfected ground water supply, in which case, a
survey must be conducted every 10 years.
The SWTR did not specifically require water systems to undergo a
sanitary survey. Instead, it required that unfiltered water systems, as
one criterion to remain unfiltered, have an annual on-site inspection
to assess the system's watershed control program and disinfection
treatment process. The on-site survey must be conducted by the State or
a party approved by the state. This on-site survey is not a substitute
for a more comprehensive sanitary survey, but the information can be
used to supplement a full sanitary survey.
USEPA's SWTR Guidance Manual (USEPA, 1991a), Appendix K, suggests
that, in addition to the annual on-site inspection, a sanitary survey
be conducted every three to five years by both filtered and unfiltered
systems. This time period is suggested ``since the time and effort
needed to conduct the comprehensive survey makes it impractical for it
to be conducted annually.''
3. New Developments
Since the publication of the proposed ESWTR in 1994, USEPA and the
States (through the Association of State Drinking Water Authorities)
have issued a joint guidance on sanitary surveys entitled USEPA/State
Joint Guidance on Sanitary Surveys (1995). The Guidance outlines the
following elements as integral components of a comprehensive sanitary
survey:
Source
--Protection
--Physical Components and Condition
Treatment
Distribution System
Finished Water Storage
Pumps/Pump Facilities and Controls
Monitoring/Reporting/Data Verification
Water System Management/Operations
Operator Compliance with State Requirements
The guidance also addresses the qualifications for sanitary survey
inspectors, the development of assessment criteria, documentation,
follow-up after the survey, tracking and enforcement.
USEPA is aware that a number of States have independently developed
their own sanitary survey criteria. For instance, the American Water
Works Association California-Nevada Section,
[[Page 59509]]
Source Water Quality Committee in conjunction with the California
Department of Health Services, Division of Drinking Water and
Environmental Management (DHS) have published a document entitled
Watershed Sanitary Survey Guidance Manual (AWWA California -Nevada
Section 1993) to assist domestic water suppliers in defining the scope
of their watershed sanitary surveys and to provide information on the
methods and sources of information for conducting sanitary surveys.
4. Advisory Committee Recommendations and Related Issues
USEPA reiterates its request for comment on the following
recommendations of the M-DBP Advisory Committee.
A sanitary survey would be defined as an onsite review of the
water source (identifying sources of contamination using results of
source water assessments where available), facilities, equipment,
operation, maintenance, and monitoring compliance of a system to
evaluate the adequacy of the system, its sources and operations and
the distribution of safe drinking water. Included in this definition
is the concept that components of a sanitary survey may be completed
as part of a staged or phased State review process within the
established frequency interval set forth below. Finally, for a
sanitary survey to fall within this definition, it must address each
of the eight elements in the December 1995 USEPA/State Guidance on
Sanitary Surveys.
In terms of frequency, this approach would provide that sanitary
surveys must be conducted for all surface water systems (including
ground water under the influence) no less frequently than every
three years for community systems and no less frequently than every
five years for noncommunity systems. Any sanitary survey conducted
after December 1995, that addresses the eight sanitary survey
components of the 1995 EPA/State guidance, may be counted or
``grandfathered'' for purposes of completing the round of surveys.
This approach would also provide that for community systems
determined by the State to have outstanding performance based on
prior sanitary surveys, successive sanitary surveys may be conducted
no less than every five years.
Finally, under this approach, as part of follow-up activity for
sanitary surveys, systems must respond to deficiencies outlined in
the State's sanitary survey report within 45 days, indicating how
and on what schedule the system will address significant
deficiencies noted in the survey. In addition, States must have the
appropriate rules or other authority to assure that facilities take
the steps necessary to address significant deficiencies identified
in the survey report that are within the control of the PWS and its
governing body.
USEPA also requests comment on whether systems should be required
to respond in writing to a State's sanitary survey report discussed in
the paragraph above. USEPA also requests comment on (1) what would
constitute ``outstanding performance'' for purposes of allowing
sanitary surveys for a community water system to be conducted every
five years and (2) how to define ``significant deficiencies.''
H. Covered Finished Water Reservoirs
1. Summary of the 1994 Proposal and Public Comments Received
The July 29, 1994, Federal Register indicated that USEPA was
considering whether to issue regulations requiring systems to cover
finished water reservoirs and storage tanks, and requested public
comment. The rationale for this position was given in the proposed
rule.
Most commenters supported either federal or State requirements.
Some commenters suggested that regulations apply only to new
reservoirs. Some commenters opposed any requirement, citing high cost,
the notion that ``one size does not fit all'', and aesthetic benefits
of an open reservoir.
Some commenters suggested elements for such regulations or
guidance, including (1) applying the same criteria to finished water
reservoirs as exists for unfiltered surface water systems, (2) using
engineering measures to minimize contamination, (3) disinfecting the
effluent to maintain residual in distribution system, (4) monitoring
reservoirs routinely for water quality indicators, (5) covering all
storage tanks, (6) fencing reservoirs with signs warning against
swimming, trespassing, and tampering, and (7) adding notices in the
annual water quality report that the reservoir is not in compliance
with current waterworks standards. A few commenters suggested a number
of other elements.
2. Overview of Existing Information
Possible Health Concerns: When a finished water reservoir is open
to the atmosphere it may be subject to some of the environmental
factors that surface water is subject to, depending upon site-specific
characteristics and the extent of protection provided. It may be
subject to contamination by persons tossing items into the reservoir or
illegal swimming (Pluntze 1974; Erb, 1989).
Microscopic and other organisms may proliferate in open finished
water reservoirs. Increases in algal cells, heterotrophic plate count
(HPC) bacteria, turbidity, color, particle counts, biomass and
decreases in chlorine residuals have been reported (Pluntze, 1974, AWWA
Committee Report, 1983, Silverman et al., 1983, LeChevallier et al.
1997a).
Small mammals, birds, fish, and the growth of algae may contribute
to the microbial degradation of an open finished water reservoir
(Graczyk et al., 1996; Geldreich, 1990; Fayer and Ungar, 1986; Current,
1986). Mammals, birds and fish and their carcasses seed the water and
the sediment with total and fecal coliforms, E. coli and pathogens. In
one study, sea gulls contaminated a 10 million gallon reservoir and
increased bacteriological growth and in another study waterfowl were
found to elevate coliform levels in small recreational lakes by twenty
times their normal levels (Morra, 1979). Seagulls are a source of
numerous coliforms and can also be a source for several human
pathogens, (Geldreich and Shaw, 1993). Algal growth increases the
biomass in the reservoir, which reduces dissolved oxygen and thereby
increases the release of iron, manganese, and nutrients from the
sediments. This, in turn, supports more growth (Cooke and Carlson,
1989). Plants, macrophytes and organic debris will add to the biomass
and nutrient supply.
State Regulations: In order to assess regulatory requirements at
the State level, it is necessary to contact individual drinking water
programs and collect and evaluate specific regulatory language obtained
from those programs. A survey of nine States was conducted in the
summer of 1996 (Montgomery Watson, 1996). The States which were
surveyed included several in the West (Oregon, Washington, California,
Idaho, Arizona, and Utah), two States in the East known to have water
systems with open reservoirs (New York and New Jersey), and one
midwestern state (Wisconsin). Seven of the nine States which were
surveyed require by direct rule that all new finished water reservoirs
and tanks be covered.
Survey of Ten Utilities: There is no comprehensive information
available on the number or size of open finished water reservoirs in
water systems around the country; however, there is one recent survey
of ten utilities which either have open finished water reservoirs or
which had them in the past and covered or replaced them (E&S
Environmental Chemistry, 1997). The existing open reservoirs which were
operated by these systems varied greatly in size, from 5.5 million
gallons (MG) to 900 MG. The systems with open finished reservoirs also
had closed reservoirs within their service area, but for some of the
systems the open reservoirs represent the largest component of total
storage volume in the systems.
[[Page 59510]]
Most of the reservoirs in the systems in this survey were excavated
and lined, but several of the larger ones were formed by dams or
natural lakes that had been converted to water supply use. Many of
these reservoirs have irregular geometry and configurations which make
covering very difficult or impossible. Others are so large that
covering them would be impractical. For some of these reservoirs, it is
impractical to find locations for replacement with the proper hydraulic
characteristics and size. To partially solve this problem in some
cases, systems have chosen to leave large existing open reservoirs off-
line, except for emergency supply purposes.
None of the systems had comprehensive evidence about the effect of
open reservoirs on water quality. These water systems had instituted a
number of measures at open reservoirs to control potential sources of
contamination; these measures included fencing setbacks, security
cameras, on-site surveillance, rechlorination, wire canopies to control
bird activity, and other measures.
3. Request for Public Comment
USEPA is considering as part of the IESWTR a requirement that
systems cover all new reservoirs, holding tanks or other storage
facilities for finished water for which construction begins after the
effective date of the rule. The Agency intends to further consider this
issue, including whether there should be a requirement that all
finished water reservoirs, holding tanks and other storage facilities
be covered, as part of the development of the Long-Term ESWTR. The
Agency requests further comment on this issue and whether provisions
should be established to require all new reservoirs, holding tanks, or
other storage facilities to be covered.
I. Cross Connection Control Program
1. Summary of 1994 Proposal and Public Comments
The July 29, 1994, Federal Register requested public comment on
whether the Agency should require States and/or systems to have a
cross-connection control program. In addition, the Agency solicited
comment on a number of associated issues, including (1) what specific
criteria, if any, should be included in such a requirement, (2) how
often such a program should be evaluated, (3) whether USEPA should
limit any requirement to only those connections identified as a cross
connection by the public water system or the State, and (4) conditions
under which a waiver from this requirement would be appropriate. The
Agency also requested commenters to identify other regulatory measures
USEPA should consider to prevent contamination of drinking water in the
distribution system (e.g., minimum pressure requirements in the
distribution system).
Most commenters supported either a federal or State cross
connection control program. Various commenters recommended that such a
program include a backflow prevention program with approved backflow
preventer lists, categorization of all service connections with respect
to potential risk of backflow, requirement for periodic testing and
maintenance of backflow prevention devices, periodic review of program
by State, establishment of an annual backflow device testing program,
establishment of a backflow device inspector certification program,
enforcement authority, and other suggestions. Commenters also
recommended national disinfection procedures for repair of water lines
and for placing new lines into service, a provision for at least one
person trained in cross-connection control to carry out the program,
and other suggestions.
Commenters opposed to a cross connection control program indicated
that (1) a federally-mandated program would be impractical, burdensome,
and would fail, (2) a State program would be more appropriate than an
USEPA-mandated program, (3) most States already have a comprehensive
program, thus negating need for federal regulations, (4) USEPA should
publish general guidelines only, and (5) there should be a separate
regulation because a cross connection control program would affect both
surface water and ground water.
2. Overview of Existing Information
Historically, a significant portion of waterborne disease outbreaks
reported by CDC are caused by distribution system deficiencies.
Distribution system deficiencies are defined in CDC's publication
Morbidity and Mortality Weekly Report as cross connections,
contamination of water mains during construction or repair, and
contamination of a storage facility. Between 1971-1994, approximately
53 waterborne disease outbreaks were associated with cross connections
or backsiphonage. Fifty-six outbreaks were associated with other
distribution system deficiencies (Craun, Pers. Comm. 1997b). Some
outbreaks have resulted from water main breaks or repairs.
There is no centralized repository where backflow incidents are
reported or recorded. The vast majority of backflow incidents are
probably not reported. Specific backflow incidents are described in
detail in USEPA's Cross-Connection Control Manual (USEPA, 1989a).
Where cross connections exist, some protection is still afforded to
the distribution system by the maintenance of a positive water pressure
in the system. Adequate maintenance of pressure provides a net movement
of water out through breaks in the distribution pipes and prevents
contaminated water outside of the pipes from entering the drinking
water supply. The loss of pressure in the distribution system, less
than 20 psi, can cause a net movement of water from outside the pipe to
the inside, possibly allowing the introduction of fecal contamination
into the system. This problem is of special concern where wastewater
piping is laid in the same street as the water pipes, creating a
potential threat to public health whenever there is low or no pressure.
Many States have cross connection control programs. A Florida
Department of Environmental Protection survey evaluated cross-
connection control regulations in the 50 states (Florida DEP 1996). The
survey results showed that 29 of the 40 states that responded to the
survey request have programs. The rigor of the programs and the extent
to which they are enforced was not addressed by the survey. An USEPA
report suggests that the responsibility for administration and
enforcement of the State programs is generally at the local level
(USEPA, 1995a).
3. Request for Public Comment
USEPA does not plan to address cross connection control in the
IESWTR. As noted above, many States currently have programs, although
the extent to which these vary is unclear. The Agency does plan to
consider cross connection control issues during the development of the
Long-Term ESWTR, in the context of a broad range of issues related to
distribution systems. USEPA continues to request comments or additional
information related to cross connection control or other distribution
system issues.
J. Recycling Filter Backwash Water and Filtering to Waste
The July 29, 1994, notice requested comment on the extent to which
the ESWTR should address the issue of recycling filter backwash water,
given its potential for increasing the densities of Giardia and
Cryptosporidium on the filters. The 1996 Amendments to the SDWA require
USEPA to promulgate a
[[Page 59511]]
regulation for filter backwash recycling not later than August 2000,
(SDWA 1412(b)(14)).
Most commenters who addressed this issue contended that backwash
water should not be recycled or that, if it is recycled, it should be
treated first. One commenter suggested that this decision should be
based on the pathogen density in the backwash water. Another commenter
suggested that the rule should include criteria for assessing the
extent of backwash recycling, depending on raw water quality, size of
filters, and water volume. Another commenter maintained that this issue
should be left to the State and system. One commenter suggested that
the impacts of recycling needed additional research and that any rule
addressing this issue needed to incorporate the results of the latest
research.
1. Filter Backwash Recycle Configurations
Treatment plants can be configured into several general categories
but the variation within each category is significant.
One aspect of this treatment variation is how recycling of waste
streams from plant processes are handled. Figure 4 shows a general
schematic of a conventional treatment plant and how recycle streams may
be developed and treated. Note that backwash water treatment is carried
out in a miniature coagulation-flocculation-sedimentation treatment
facility. Some utilities are considering microfiltration to replace
these unit processes.
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[[Page 59512]]
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[[Page 59513]]
Figure 5 shows an alternate view for some water treatment
facilities that do not practice treatment of their recycled waste
streams. There is an almost infinite variety between these two
examples. In addition, waste streams can be recycled to many different
points in the treatment train. The most common recycle points are at
the plant influent or rapid mix. However, there are several known
examples of recycle streams being introduced into the treatment process
as late as the filter influent.
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Figure 6 shows a typical plot of turbidity over time from a filter
from reintroduction into service after backwash to breakthrough of
turbidity at the end of the filter run. Some plants have installed
filter-to-waste facilities which allow the discharge of the first
minutes of a filter's operation after backwashing usually into the
backwash reclamation system. In California, the State drinking water
regulations define filter-to-waste as: ` ``Filter-to-waste'' means a
provision in a filtration process to allow the first filtered water,
after backwashing a filter, to be wasted or reclaimed.' (McGuire, 1994)
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[[Page 59514]]
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Figure 7 shows a general schematic of a filter-to-waste operation.
After the backwash process is complete and the filter influent water is
allowed to enter the filter, Valve A is operated so that all of the
filter effluent water is sent to waste. After a specified period of
time or when it is determined that the ripening spike is largely over,
Valve A is operated so that the filtered water becomes part of the
product water of the treatment plant.
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[[Page 59515]]
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BILLING CODE 6560-50-C
2. State Drinking Water Regulations
California has specific regulations that deal with backwash recycle
and filter-to-waste. Treatment of backwash recycle flows is covered in
the design of treatment facilities section. For new construction,
utilities are required to install solids removal treatment for recycled
filter backwash water. Also, treated backwash water must be returned to
the ``headworks'' (i.e., the plant influent) of the treatment plant.
Solids removal treatment unit processes are not specified in the
regulation, but new construction must be approved by the California
Department of Health Services (California Health and Safety Code,
Sections 646658 & 64660).
To minimize the filter ripening spike, the California Department of
Health specifies operational requirements such that filtration rates
are increased gradually when filters are placed back into service
following backwashing or any other interruption in the operation of the
filter. When any individual filter is placed back into service
following backwashing or other interruption event, the filtered water
turbidity from that filter cannot exceed any of the following criteria:
2.0 NTU.
1.0 NTU in at least 90 percent of the interruption events
during any consecutive 12-month period.
0.5 NTU after the filter has been in operation for 4
hours.
For new construction, utilities are required to provide filter-to-
waste or add additional coagulant chemicals to backwash water.
3. Literature Overview of Standard of Practice
a. Treatment Reference Texts. The joint ASCE/AWWA (1990) water
treatment plant design book includes one section on page 182 dealing
with washwater disposal and recovery. The section lists several
possibilities including recycling without treatment, equalization and
treatment, and lagoons to provide for both equalization and
sedimentation. On page 188, the backwash recycle facility at the
Duluth, Minnesota plant is described. Chemical addition, flocculation
and clarification comprise the backwash treatment system.
The fourth edition of Water Quality and Treatment contains one
section on pages 988-989 dealing with filter backwash residuals. The
section notes that recovery of ``dirty'' backwash water is becoming
increasingly common and that the volume of backwash water is typically
one to five percent of total plant production. Flow equalization is
listed as the most common approach to dealing with recycling of
backwash water. The section states that ``For conventional plants,
solid separation before return is not common, and some holding tanks
are mixed to keep solids in suspension.'' Direct filtration plants are
noted for needing solids separation
[[Page 59516]]
treatment of backwash water, because there is no sedimentation facility
in a direct filtration plant. Concerns are expressed in the section
about increasing the concentrations of Giardia cysts in the plant
influent with the recycle of untreated backwash water.
A handbook of practice was published in 1987 dealing with water
treatment plant waste management. Backwash water was described as a
major waste stream on page 5 and flow equalization was listed as an
important requirement. The handbook gives specific examples of the size
of backwash basins needed based on the number of filters backwashed and
the backwash frequency. The example discusses tankage volumes that
would allow a maximum 10 percent recycle rate of the backwash water to
the plant influent. Neither clarification nor polymer addition were
mentioned in this early reference (Cornwell et al., 1987).
b. ICR Treatment Plants. Of the 523 treatment plants subject to the
ICR, 282 use conventional treatment. Of the conventional treatment
plants, 146 (or 52%) practice recycling of their backwash water.
Additionally, 15 direct filtration plants and 3 in-line filter plants
recycle their backwash water. These data show that a large fraction of
the surface water treatment plants recycle their backwash water.
The ICR will provide the first detailed data on the number of
treatment plants that treat their recycled backwash water and the
technologies they use and some limited data on backwash water quality.
Until the initial sampling plan data is available for analysis sometime
in early 1998, the only information available on the ICR utilities is
from their Initial Sampling Schematics and that will only show the
addition of a treatment chemical. The Initial Sampling Schematics do
not indicate if coagulation, flocculation or sedimentation is used for
washwater recycle treatment.
An inspection of those schematics revealed the following
information on treatment of recycled backwash water. A total of 164
schematics for plants using conventional treatment, direct filtration
or in-line filtration were examined. Only 12 of the plants indicated
that they provided any chemical treatment. Addition of a polymer was
practiced at 5 plants. Chlorination as the only treatment of the
recycled washwater was found at 2 plants. A total of 5 plants provided
both chlorination and polymer treatment of the backwash water.
c. Cornwell and Lee 1993 Report. Another source of information on
waste stream quality and the impact of recycling of these streams on
treated water quality is found in an American Water Works Association
Research Foundation (AWWARF) 1993 report authored by Cornwell and Lee.
They studied the quality characteristics of waste streams from 24
treatment plants and investigated the treatment characteristics in some
detail at 8 plants.
Among the contaminants analyzed were Giardia and Cryptosporidium.
The study found that filter backwash water could have very high cyst/
oocyst concentrations and chemical loads. However, the researchers
found no finished water quality problems as a result of recycling.
The study found that backwash water sedimentation was effective in
reducing particle and pathogen concentrations in the used filter
backwash water. However, very low overflow rates (less than 0.05 gpm/
sf) of the sedimentation basin were required to achieve the solids
removal unless a polymer was used. Using an anionic polymer increased
the particle removals and allowed sedimentation overflow rates of 0.2
to 0.3 gpm/sf. The last two sentences of the Executive Summary of the
report provide insight into the overall findings.
``The use of equalized, continuous recycle, proper waste stream
treatment prior to recycle, and characterization of waste stream
quality through proper monitoring should be used in conjunction with
recycle operations. If these recommendations are used, recycle can
be an appropriate part of water treatment operations (Cornwell and
Lee, 1993).''
In a paper which summarized the report findings, the authors stated
a general rule that the recycle streams should be flow equalized and
blended in to the plant flow over the entire 24 hour plant operating
cycle. The rule of thumb that the amount of recycle should be less than
10 percent of the plant flow may not be sufficient, and a lower
percentage of recycle may have to be practiced depending on the quality
of the recycled water (Cornwell and Lee, 1994).
d. Other Studies. In 1996, AWWA conducted a survey of treatment
plants to determine the extent of backwash water recycling and the
treatment provided to that water (McGuire, 1997). A total of 400 plants
from utilities serving more than 100,000 people were contacted. About
40 percent of those plants responded. Of those responding, about 60
percent of the plants recycled their filter backwash water. The other
40 percent appeared to discharge the backwash water to a surface water
supply or to a sanitary sewer. Of the plants that recycled their
backwash water, 27 percent responded that they treated the recycle
water. The important point to note from this limited survey is that
recycle of backwash water appears to be a common practice among water
treatment plants.
4. Filter-to-Waste
One possible concern is the discharge of large number of particles
from filters that are put back into service after backwashing. Work
done on Giardia removal by filtration at Fort Collins, Colorado,
indicated that a filter-to-waste period was not necessary to produce
low Giardia filter effluent levels as long as proper chemical
preconditioning of the filter was practiced (Gertig et al. 1988).
Logsdon et al. studied sedimentation and several different filter media
from removing Giardia cysts at McKeesport, Pennsylvania. Giardia cyst
concentrations were found to be higher at the beginning of the filter
run, indicating that filter-to-waste may be needed to reduce the levels
of Giardia in the finished water (Logsdon et al, 1985).
One study (Amirtharajah, 1988) indicated that more than 90% of the
particles that pass through a filter do so during the initial stages of
filtration. Another study (Logsdon et al., 1981) found that initial
cyst concentrations in the effluent, after backwash, were from 10 to 25
times higher than those in the stabilized filter run, even though the
difference in turbidity was less than 0.1 NTU. One British study (Hall
and Croll 1996) found that in one test filter run, calculation of the
total number of particles released during the whole run showed that up
to 30% of the particles were released during the first hour of filter
ripening. The turbidity during this peak was 0.4 NTU. Gradual start of
the filter after backwashing reduced the peak particle count in the
effluent. Effectiveness of practicing filter-to-waste in reducing the
passing of oocysts depends on the duration of the ripening period. For
example, a 15 minute filter-to-waste period will not be very effective
for a ripening period of 2 hours. Mid and end-of-run turbidity spikes
can also pass large number of particles (including pathogen oocysts)
into the effluent. However, these latter spikes can be controlled by
avoidance of flow changes and by timely backwashing the filter.
5. Request for Public Comment
USEPA does not plan to include separate provisions for recycling of
filter backwash water and filter-to-waste issues in the IESWTR. The
Agency anticipates that some systems will address these issues as part
of their efforts to comply with revised turbidity performance standards
of 0.3 NTU for
[[Page 59517]]
the 95th percentile of monthly measurements and a maximum turbidity
level of 1 NTU. As previously discussed in this Notice, USEPA is
required under the 1996 Amendments to the SDWA to issue a regulation to
address filter backwash recycling by August 2000. USEPA plans to
develop these regulations in conjunction with the development of the
Long-Term ESWTR. USEPA continues to request comments or additional
information related to recycling of filter backwash water or filter-to-
waste issues.
K. Certification Criteria for Water Plant Operators
The July 29, 1994, notice requested comment on whether the ESWTR
should define minimum certification criteria for surface water
treatment plant operators. Currently, the SWTR (141.70) requires such
systems to be operated by ``qualified personnel who meet the
requirements specified by the State.'' The 1996 Amendments to the SDWA
require USEPA to undertake several actions with regard to operator
certification, including the publication of guidelines specifying
minimum standards.
Of the few commenters who addressed this issue most asserted that
minimum certification criteria for water operators should be left to
the States. One commenter contended that certified operator(s) should
be on site at all times and that a non-certified operator should never
be in charge. Another respondent noted that rewording Sec. 141.70 to
read ``personnel who are certified by the State, or can obtain
certification within one year of date of employment'' will adequately
define certification criteria.
Consistent with the 1996 SDWA amendments, USEPA appointed an
Operator Certification Working Group of the National Drinking Water
Advisory Council (NDWAC) to form a partnership with States, water
systems and the public to develop information on recommended operator
certification requirements. USEPA will publish guidelines specifying
minimum standards for certification (and recertification) of operators
of community and nontransient noncommunity public water systems. USEPA
is developing the draft guidelines based on recommendations from the
NDWAC. The draft guidelines, when available, will be published in the
Federal Register for public review and comment. Members of the public
who are interested in further information regarding this effort may
contact Richard Naylor of USEPA's Office of Ground Water and Drinking
Water at 202-260-5135 or at e-mail address:
naylor.richard@epamail.epa.gov.
L. Regulatory Compliance Schedule and Other Compliance-Related Issues
A. Regulatory Compliance Schedule
Background
During the 1992 Disinfectants/Disinfection Byproducts Regulatory
Negotiation (reg-neg) that resulted in the 1994 proposed Stage 1 DBPR
and proposed IESWTR, there was extensive discussion of the compliance
schedule and applicability to different groups of systems and
coordination of timing with other regulations.
In addition to the Stage 1 DBPR, the Negotiating Committee agreed
that EPA would (a) propose an interim ESWTR which would apply to
surface water systems serving 10,000 or more people, and (b) at a later
date, propose a long-term ESWTR applying primarily to small systems
under 10,000. Both of these microbial rules would be proposed and
promulgated so as to be in effect at the same time that systems of the
respective size categories would be required to comply with new
regulations for disinfectants and DBPs. Finally, although the GWDR was
not specifically addressed during the reg-neg, EPA anticipated that it
would be promulgated at about the same time as the IESWTR and Stage 1
DBPR.
EPA proposed a staggered compliance schedule, based on the reg-neg
results. The Negotiating Committee and EPA believed that such a process
was needed for the rules to be properly implemented by both States and
PWSs. Also, EPA proposed a staggered schedule to achieve the greatest
risk reduction by providing that larger water systems were to come into
compliance earlier than small systems (to cover more people earlier),
and surface water systems were to come into compliance earlier than
ground water systems (since the potential risks of both pathogens and
DBPs were considered generally higher for surface water systems). Large
and medium size surface water PWSs (serving at least 10,000 people)
constitute less than 25% of community water systems using surface water
and less than 3% of the total number of community water systems, but
serve 90% of the population using surface water and over 60% of the
population using water from community water systems. These large PWSs
are also those with experience in simultaneous control of DBPs and
microbial contaminants. EPA proposed that these systems be required to
comply with the Stage 1 DBPR and IESWTR 18 months after promulgation of
the rules and that States would be required to adopt the rules no later
than 18 months after promulgation. These 18 month periods were
prescribed in the 1986 SDWA Amendments.
Surface water PWSs serving fewer than 10,000 people were to comply
with the Stage 1 DBPR requirements 42 months after promulgation, to
allow such systems to simultaneously come into compliance with the
LTESWTR. This compliance date reflected a schedule that called for the
LTESWTR to be promulgated 24 months after the IESWTR was promulgated
and for PWSs then to have 18 months to come into compliance. Such a
simultaneous compliance schedule was intended to provide the necessary
protection from any downside microbial risk that might otherwise result
when systems of this size attempted to achieve compliance with the
Stage 1 DBPR.
Ground water PWSs serving at least 10,000 people would also be
required to achieve compliance with the Stage 1 DBPR 42 months after
promulgation. A number of these systems, due to recently installing or
upgrading to meet the GWDR (which EPA planned to promulgate at about
the same time as the Stage 1 DBPR), were expected to need some period
of monitoring for DBPs in order to adjust their treatment processes to
also meet the Stage 1 DBPR standards.
1996 Safe Drinking Water Act Amendments
The SDWA 1996 Amendments affirmed several key principles underlying
the M-DBP compliance strategy developed by EPA and stakeholders as part
of the 1992 Regulatory Negotiation process. First, under Section
1412(b)(5)(A), Congress recognized the critical importance of
addressing risk/risk tradeoffs in establishing drinking water standards
and gave EPA the authority to take such risks into consideration in
setting MCL or treatment technique requirements. Second, Congress
explicitly adopted the staggered M-DBP regulatory development schedule
developed by the Negotiating Committee. Section 1412(b)(2)(C) requires
that the standard setting intervals laid out in EPA's proposed ICR rule
be maintained even if promulgation of one of the M-DBP rules was
delayed. As noted above, this staggered regulatory schedule was
specifically designed as a tool to minimize risk/risk tradeoff. A
central component of this approach was the concept of ``simultaneous
compliance'' which provides that a PWS must comply with new microbial
and DBP requirements at the same time to assure
[[Page 59518]]
that in meeting a set of new requirements in one area, a facility does
not inadvertently increase the risk (i.e., the risk ``tradeoff'') in
the other area.
The SDWA 1996 Amendments also changed two statutory provisions that
elements of the 1992 Negotiated Rulemaking Agreement were based upon.
As outlined above, the 1994 Stage 1 DBPR and ICR proposals provided
that 18 months after promulgation large PWSs would comply with the
rules and States would adopt and implement the new requirements.
Section 1412(b)(10) of the SDWA as amended now provides that drinking
water rules shall become effective 36 months after promulgation (unless
the Administrator determines that an earlier time is practicable or
that additional time for capital improvements is necessary--up to two
years). In addition, Section 1413(a)(1) now provides that States have
24 instead of the previous 18 months to adopt new drinking water
standards that have been promulgated by EPA.
Discussion
In light of the 1996 SDWA amendments, developing a compliance
deadline strategy that encompasses both the Stage 1 DBPR and IESWTR, as
well the related LTESWTR and Stage 2 DBPR, is a complex challenge. On
the one hand, such a strategy needs to reflect new statutory
provisions. On the other, it needs to continue to embody key reg-neg
principles reflected in both the 1994 ICR and Stage 1 DBPR proposals;
principles that both Congressional intent and the structure of the new
Amendments, themselves, indicate must be maintained.
An example of the complexity that must be addressed is the
relationship between the principles of risk/risk tradeoff, simultaneous
compliance, and the staggered regulatory schedule adopted by Congress.
Under the 1996 SDWA amendments, the staggered regulatory deadlines
under Section 1412(b)(2)(C) call for the IESWTR and Stage 1 DBPR to be
promulgated in November 1998 and the LTESWTR in November of 2000.
However, a complicating factor reflected in the Negotiated Rulemaking
Agreement of 1992 and contained in the 1994 ICR, IESWTR, and Stage 1
DBPR proposals, is that Stage 1 applies to all PWSs, while IESWTR
applies only to PWSs over 10,000, and the LTESWTR covers remaining
surface water systems under 10,000.
One approach might be to simply provide that each M-DBP rule
becomes effective 3 years after promulgation in accordance with the new
SDWA provisions. For surface water systems over 10,000, each plant
would be required to comply with related microbial and DBP requirements
at the same time thereby minimizing potential risk/risk tradeoffs. For
surface water systems under 10,000, however, this approach would result
in a very large number of smaller plants complying with DBP
requirements two years before related LTESWTR microbial provisions
became effective, thereby creating an unbalanced risk tradeoff
situation that the Negotiating Committee, EPA, and Congress each sought
to avoid.
As this example suggests, given the staggered regulatory
development schedule developed by stakeholders in the reg-neg process
and adopted by Congress, there is a difficult inconsistency between the
principle of avoiding risk tradeoffs, simultaneous compliance, and
simply requiring all facilities to comply with applicable M-DBP rules
three years after their respective promulgation. The challenge, then,
is to give the greatest possible meaning to each of the new SDWA
provisions while adhering to the fundamental principles also endorsed
by Congress of addressing risk-risk tradeoffs and assuring simultaneous
compliance.
A further question that must be factored into this complex matrix
is how to address the relationship between promulgation of a particular
rule, its effective date, and its adoption by a primacy State
responsible for implementing the Safe Drinking Water Act. Under the
1994 IESWTR and Stage 1 DBPR proposals, the rule's 18 month effective
date was the same as the 18 month date by which a State was required to
adopt it. This approach reflected the 18 month SDWA deadlines
applicable during reg-neg negotiations and at the time of proposal.
The difficulty with requiring PWS compliance and State
implementation by the same date is that States may not have enough lead
time to adopt rules, train their own staff, and develop policies to
implement and enforce new rules by the deadline for PWS compliance. In
situations where the new rules are complex and compliance requires
state review and ongoing interaction with PWSs, successful
implementation can be very difficult, particularly for States with many
small systems that have smaller staffs and fewer resources to
anticipate the requirements of final rules. As noted above, Congress
addressed this issue by extending the time for States to put their own
rules in place from 18 months to two years after federal promulgation
and, then, by generally providing for a one year interval before PWSs
must comply (three years after promulgation). As a result, the 18 month
interval contemplated by the 1994 proposals is no longer applicable,
and the approach of setting the same date for PWS compliance and State
rule implementation is no longer consistent with the phased approach
laid out in the new SDWA amendments.
A final set of issues that must be addressed in connection with the
Stage 1 DBPR proposal are compliance deadlines for ground water systems
that currently disinfect. Reflecting the Negotiated Rulemaking
Agreement, the 1994 proposal provided that ground water systems serving
at least 10,000 that disinfect must comply three and one half years (42
months) after Stage 1 DBPR promulgation. Small ground water systems
serving fewer than 10,000 that disinfect would be required to come into
compliance five years (60 months) after Stage 1 DBPR promulgation.
Again, the challenge here is to reconcile new statutory compliance
provisions with the principles of simultaneous compliance, avoiding
risk/risk tradeoffs, and deference to Congress' clear intent to
preserve the ``delicate balance that was struck by the parties in
structuring the negotiated rulemaking agreement''. (Joint Explanatory
Statement of the Committee on Conference on S.1316, p2). An additional
factor that must be considered in this context is that Congress
affirmed the need for microbial ground water regulations but also
clearly contemplated that such standards might not be promulgated until
issuance of Stage 2 DBPR (no later than May, 2002).
Alternative Approaches
In light of the 1996 SDWA amendments and their conflicting
implications for different elements of the compliance strategy agreed
to by the Negotiating Committee and set forth in the 1994 IESWTR and
Stage 1 DBPR proposals, EPA is today requesting comment on four
alternative compliance approaches. The Agency also requests comment on
any other compliance approaches or modifications to these options that
commenters believe may be appropriate.
[[Page 59519]]
Option 1.--Implement 1994 Proposal Schedule
----------------------------------------------------------------------------------------------------------------
Surface water PWS Ground water PWS
Rule (promulgation) ---------------------------------------------------------
10k <10k>10k <10k ----------------------------------------------------------------------------------------------------------------="" dbp="" 1="" (11/98).........................................="" 5/00="" 5/02="" 5/02="" 11/03="" ieswtr="" (11/98)........................................="" 5/00="" na="" na="" na="" lteswtr="" (11/00).......................................="" \1\="" 5/02="" 5/02="" na="" na="" gwdr="" (11/00)..........................................="" na="" na="" (\2\)="" (\2\)="" ----------------------------------------------------------------------------------------------------------------="" \1\="" (if="" required).="" \2\="" not="" addressed.="" option="" 1="" (schedule="" as="" proposed="" in="" 1994)="" simply="" continues="" the="" compliance="" strategy="" laid="" out="" in="" the="" 1994="" stage="" 1="" dbpr="" and="" ieswtr="" proposals.="" this="" would="" provide="" that="" medium="" and="" large="" surface="" water="" pwss="" (those="" serving="" at="" least="" 10,000="" people)="" comply="" with="" the="" final="" stage="" 1="" dbpr="" and="" ieswtr="" within="" 18="" months="" after="" promulgation,="" and="" that="" surface="" water="" systems="" serving="" fewer="" than="" 10,000="" comply="" within="" 42="" months="" of="" stage="" 1="" dbpr="" promulgation.="" this="" option="" also="" would="" provide="" that="" ground="" water="" systems="" serving="" at="" least="" 10,000="" and="" that="" disinfect="" comply="" within="" 42="" months,="" while="" ground="" water="" systems="" serving="" fewer="" than="" 10,000="" comply="" within="" 60="" months.="" this="" approach="" was="" agreed="" to="" by="" epa="" and="" other="" stakeholder="" members="" of="" the="" 1992="" negotiating="" committee.="" however,="" it="" has="" been="" at="" least="" in="" part="" superseded="" by="" both="" the="" general="" 36="" month="" pws="" compliance="" period="" and="" the="" 24="" month="" state="" adoption="" and="" implementation="" period="" provided="" under="" the="" 1996="" sdwa="" amendments.="" if="" the="" proposed="" 1994="" compliance="" schedule="" were="" to="" be="" retained,="" epa="" would="" need="" to="" make="" a="" determination="" that="" the="" statutory="" compliance="" provision="" of="" 36="" months="" was="" not="" necessary="" for="" large="" and="" medium="" surface="" systems="" because="" compliance="" within="" 18="" months="" is="" ``practicable''.="" to="" maintain="" simultaneous="" compliance,="" the="" agency="" would="" also="" have="" to="" make="" the="" same="" practicability="" determination="" for="" small="" surface="" water="" systems="" in="" complying="" with="" the="" lteswtr="" and="" for="" ground="" water="" systems="" serving="" at="" least="" 10,000="" in="" complying="" with="" the="" gwdr.="" in="" addition,="" the="" agency="" would="" need="" to="" justify="" 42="" months="" for="" small="" surface="" water="" systems="" and="" 60="" months="" for="" small="" ground="" water="" systems="" with="" disinfection="" by="" making="" a="" national="" determination="" that="" the="" additional="" time="" was="" required="" due="" to="" the="" need="" for="" capital="" improvements="" at="" each="" of="" these="" small="" systems.="" epa="" also="" would="" need="" to="" articulate="" a="" rationale="" for="" why="" states="" should="" not="" be="" provided="" the="" statutorily="" specified="" 24="" months="" to="" implement="" new="" complex="" regulatory="" provisions="" before="" pwss="" are="" required="" to="" comply.="" finally,="" to="" implement="" this="" approach,="" the="" agency="" would="" be="" required="" to="" modify="" the="" timing="" associated="" with="" the="" microbial="" backstop="" provision="" agreed="" to="" on="" july="" 15,="" 1997="" by="" the="" m-dbp="" advisory="" committee="" (since="" a="" 18="" month="" schedule="" would="" not="" allow="" time="" after="" promulgation="" for="" medium="" surface="" water="" systems="" (10,000-99,999)="" to="" collect="" haa="" data="" prior="" to="" having="" to="" determine="" whether="" disinfection="" benchmarking="" is="" necessary).="" epa="" requests="" comment="" on="" the="" issues="" outlined="" above="" in="" connection="" with="" this="" option.="" in="" particular,="" the="" agency="" requests="" comment="" and="" information="" to="" support="" a="" finding="" that="" compliance="" by="" specified="" systems="" in="" 18="" months="" is="" practicable="" for="" some="" rules,="" and="" that="" extensions="" to="" 42="" or="" 60="" months="" for="" other="" systems="" are="" required="" to="" allow="" for="" capital="" improvements.="" option="" 2.--add="" 18="" months="" to="" 1994="" proposal="" schedule="" ----------------------------------------------------------------------------------------------------------------="" surface="" water="" pws="" ground="" water="" pws="" rule="" (promulgation)="" ---------------------------------------------------------="">10k <10k>10k <10k ----------------------------------------------------------------------------------------------------------------="" dbp="" 1="" (11/98).........................................="" 11/01="" 11/03="" 11/03="" 5/05="" ieswtr="" (11/98)........................................="" 11/01="" na="" na="" na="" lteswtr="" (11/00).......................................="" \1\="" 11/03="" 11/03="" na="" na="" gwdr="" (11/00)..........................................="" na="" na="" (\2\)="" (\2\)="" ----------------------------------------------------------------------------------------------------------------="" \1\="" (if="" required).="" \2\="" not="" addressed.="" option="" 2="" (each="" date="" in="" proposed="" 1994="" compliance="" strategy="" extended="" by="" 18="" months)="" reflects="" the="" fact="" that="" the="" 1996="" sdwa="" amendments="" generally="" extended="" the="" previous="" statutory="" deadlines="" by="" 18="" months="" (to="" three="" years)="" and="" established="" an="" overall="" compliance="" period="" not="" to="" extend="" beyond="" 5="" years.="" this="" second="" approach="" would="" result="" in="" simultaneous="" compliance="" for="" surface="" water="" systems.="" large="" surface="" water="" systems="" (those="" serving="" at="" least="" 10,000)="" would="" have="" three="" years="" to="" comply="" in="" accordance="" with="" the="" baseline="" 3="" year="" compliance="" period="" established="" under="" section="" 1412(b)(10)="" of="" the="" 1996="" amendments.="" small="" surface="" water="" systems="" (under="" 10,000)="" would="" be="" required="" to="" comply="" with="" stage="" 1="" d/dbpr="" requirements="" within="" five="" years="" and="" applicable="" lteswtr="" requirements="" within="" three="" years.="" since="" the="" lteswtr="" will="" be="" promulgated="" two="" years="" after="" stage="" 1="" dbpr="" (in="" accordance="" with="" the="" new="" sdwa="" m-dbp="" regulatory="" deadlines="" discussed="" above),="" the="" net="" result="" of="" this="" approach="" is="" that="" small="" surface="" water="" systems="" would="" be="" required="" to="" comply="" with="" both="" stage="" 1="" dbpr="" and="" ieswtr="" requirements="" by="" the="" same="" end="" date="" of="" november="" 2003,="" thus="" assuring="" simultaneous="" compliance.="" this="" meets="" the="" objective="" of="" both="" the="" reg-neg="" process="" and="" congress="" to="" address="" risk-risk="" tradeoffs="" in="" implementing="" new="" m-dbp="" requirements.="" usepa="" believes="" that="" providing="" a="" five="" year="" compliance="" period="" for="" small="" surface="" water="" systems="" under="" the="" stage="" 1="" dbpr="" is="" appropriate="" and="" warranted="" under="" section="" 1412(b)(10),="" which="" expressly="" allows="" five="" years="" where="" necessary="" for="" capital="" improvements.="" of="" necessity,="" capital="" improvements="" require="" [[page="" 59520]]="" preliminary="" planning="" and="" evaluation.="" such="" planning="" requires,="" perhaps="" most="" importantly,="" identification="" of="" final="" compliance="" objectives.="" this="" then="" is="" followed="" by="" an="" evaluation="" of="" compliance="" alternatives,="" site="" assessments,="" consultation="" with="" appropriate="" state="" and="" local="" authorities,="" development="" of="" final="" engineering="" and="" construction="" designs,="" financing,="" and="" scheduling.="" in="" the="" case="" of="" the="" staggered="" m-dbp="" regulatory="" schedule="" established="" as="" part="" of="" the="" 1996="" sdwa="" amendments,="" lteswtr="" microbial="" requirements="" for="" small="" systems="" are="" required="" to="" be="" promulgated="" two="" years="" after="" the="" establishment="" of="" stage="" 1="" dbpr="" requirements.="" under="" these="" circumstances,="" small="" systems="" will="" not="" even="" know="" what="" their="" final="" combined="" m-dbp="" compliance="" obligations="" are="" until="" federal="" register="" publication="" of="" the="" final="" lteswtr.="" as="" a="" result,="" an="" additional="" two="" year="" period="" reflecting="" the="" two="" year="" stage="" 1="" dbpr/lteswtr="" regulatory="" development="" interval="" established="" by="" congress="" is="" required="" to="" allow="" for="" preliminary="" planning="" and="" evaluation="" which="" is="" an="" inherent="" component="" of="" any="" capital="" improvement="" process.="" epa="" believes="" this="" approach="" is="" consistent="" with="" both="" the="" objective="" of="" assuring="" simultaneous="" compliance="" and="" not="" exceeding="" the="" overall="" statutory="" compliance="" period="" of="" five="" years.="" this="" same="" logic="" would="" also="" apply="" to="" ground="" water="" systems="" serving="" at="" least="" 10,000,="" since="" such="" systems="" would="" need="" the="" final="" gwdr="" to="" determine="" and="" implement="" a="" compliance="" strategy.="" with="" regard="" to="" extended="" compliance="" schedules,="" epa="" notes="" that="" the="" economic="" analysis="" developed="" as="" part="" of="" the="" m-dbp="" advisory="" committee="" indicates="" that="" there="" will="" be="" capital="" costs="" associated="" with="" implementation="" of="" both="" the="" ieswtr="" as="" well="" as="" the="" stage="" i="" dbp="" rules.="" as="" outlined="" above,="" the="" 1996="" sdwa="" amendments="" provide="" that="" a="" two="" year="" extension="" may="" be="" provided="" by="" epa="" at="" the="" national="" level="" or="" by="" states="" on="" a="" case-by-case="" basis="" if="" either="" epa="" or="" a="" state="" determines="" that="" additional="" time="" is="" necessary="" for="" capital="" improvements.="" epa="" does="" not="" believe="" there="" is="" data="" presently="" in="" the="" record="" for="" either="" of="" these="" rulemakings="" to="" support="" a="" national="" determination="" by="" the="" agency="" that="" a="" two-year="" extension="" is="" justified.="" epa="" requests="" comment="" on="" this="" issue="" and,="" if="" a="" commenter="" believes="" such="" an="" extension="" is="" warranted,="" requests="" that="" the="" comments="" provide="" data="" to="" support="" such="" a="" position.="" adding="" 18="" months="" to="" the="" 1994="" proposed="" compliance="" strategy="" would="" result="" in="" 78="" month="" (six="" and="" a="" half="" year)="" compliance="" period="" for="" small="" ground="" water="" systems.="" this="" is="" beyond="" the="" overall="" five="" year="" compliance="" period="" established="" by="" congress="" under="" section="" 1412(b)(10).="" epa="" is="" not="" aware="" of="" a="" rationale="" to="" support="" this="" result="" that="" is="" consistent="" with="" both="" the="" objectives="" of="" the="" reg-neg="" process="" and="" the="" new="" sdwa="" amendments;="" however,="" the="" agency="" requests="" comment="" on="" this="" issue.="" as="" discussed="" below,="" epa="" believes="" there="" is="" a="" reasonable="" compliance="" strategy="" for="" addressing="" ground="" water="" systems="" that="" reflects="" the="" requirements="" of="" the="" sdwa="" amendments="" as="" well="" as="" the="" intent="" of="" the="" reg-neg="" process.="" option="" 3.--require="" compliance="" with="" all="" rules="" within="" three="" years="" of="" promulgation="" ----------------------------------------------------------------------------------------------------------------="" surface="" water="" pws="" ground="" water="" pws="" rule="" (promulgation)="" ---------------------------------------------------------="">10k <10k>10k <10k ----------------------------------------------------------------------------------------------------------------="" dbp="" 1="" (11/98).........................................="" 11/01="" 11/01="" 11/01="" 11/01="" ieswtr="" (11/98)........................................="" 11/01="" na="" na="" na="" lteswtr="" (11/00).......................................="" \1\="" 11/03="" 11/03="" na="" na="" gwdr="" (11/00)..........................................="" na="" na="" 11/03="" 11/03="" ----------------------------------------------------------------------------------------------------------------="" \1\="" (if="" required).="" under="" this="" approach,="" all="" systems="" would="" be="" required="" to="" comply="" with="" stage="" 1="" dbpr,="" ieswtr,="" and="" lteswtr="" within="" three="" years="" of="" final="" promulgation.="" this="" approach="" reflects="" the="" baseline="" three="" year="" compliance="" period="" included="" as="" part="" of="" the="" new="" sdwa="" compliance="" provisions.="" unlike="" option="" 2="" outlined="" above="" which="" simply="" adds="" an="" 18="" month="" extension="" to="" the="" 1994="" proposed="" compliance="" approach,="" this="" option="" is="" not="" tied="" to="" the="" 1994="" proposal.="" rather="" it="" applies="" the="" new="" baseline="" three="" year="" compliance="" period="" to="" the="" staggered="" m-dbp="" regulatory="" development="" schedule="" which="" was="" also="" established="" as="" part="" of="" the="" 1996="" sdwa="" amendments.="" this="" approach="" would="" result="" in="" simultaneous="" compliance="" for="" large="" surface="" water="" systems.="" however,="" it="" would="" eliminate="" the="" possibility="" of="" simultaneous="" compliance="" for="" small="" surface="" water="" systems="" and="" all="" ground="" water="" systems.="" contrary="" to="" reg-neg="" objectives="" and="" congressional="" intent,="" it="" would="" create="" an="" incentive="" for="" risk/risk="" tradeoffs="" on="" the="" part="" of="" small="" surface="" water="" systems="" who="" would="" be="" required="" to="" take="" steps="" to="" comply="" with="" stage="" 1="" dbpr="" provisions="" two="" years="" before="" coming="" into="" compliance="" with="" the="" lteswtr,="" and="" for="" all="" ground="" water="" systems="" who="" would="" be="" required="" to="" take="" steps="" to="" comply="" with="" stage="" 1="" dbpr="" provisions="" two="" years="" before="" coming="" into="" compliance="" with="" the="" gwdr.="" option="" 4.--merge="" sdwa="" provisions="" with="" negotiated="" rulemaking="" objectives="" ----------------------------------------------------------------------------------------------------------------="" surface="" water="" pws="" ground="" water="" pws="" rule="" (promulgation)="" ---------------------------------------------------------="">10k <10k>10k <10k ----------------------------------------------------------------------------------------------------------------="" dbp="" 1="" (11/98).........................................="" 11/01="" 11/03="" 11/03="" 11/03="" ieswtr="" (11/98)........................................="" 11/01="" na="" na="" na="" lteswtr="" (11/00).......................................="" \1\="" 11/03="" 11/03="" na="" na="" gwdr="" (11/00)..........................................="" na="" na="" 11/03="" 11/03="" ----------------------------------------------------------------------------------------------------------------="" \1\="" (if="" required).="" this="" option="" combines="" the="" principle="" of="" simultaneous="" compliance="" with="" the="" revised="" compliance="" provisions="" reflected="" in="" the="" 1996="" sdwa="" amendments.="" large="" surface="" water="" systems="" would="" be="" required="" to="" comply="" with="" stage="" 1="" dbpr="" [[page="" 59521]]="" and="" ieswtr="" within="" 3="" years="" of="" promulgation,="" thus="" assuring="" simultaneous="" compliance="" and="" consistency="" with="" the="" baseline="" statutory="" compliance="" period="" of="" 3="" years.="" small="" surface="" water="" systems="" under="" 10,000="" would="" comply="" with="" the="" provisions="" of="" the="" stage="" 1="" dbpr="" at="" the="" same="" time="" they="" are="" required="" to="" come="" into="" compliance="" with="" the="" analogous="" microbial="" provisions="" of="" the="" lteswtr.="" this="" would="" result="" in="" small="" surface="" water="" systems="" simultaneously="" complying="" with="" both="" the="" lteswtr="" and="" stage="" 1="" dbpr="" requirements.="" under="" this="" approach,="" small="" systems="" would="" comply="" with="" lteswtr="" requirements="" three="" years="" after="" promulgation="" and="" stage="" 1="" dbpr="" requirements="" five="" years="" after="" promulgation.="" for="" the="" reasons="" articulated="" under="" option="" two="" above,="" epa="" believes="" providing="" a="" five="" year="" compliance="" period="" under="" stage="" 1="" dbpr="" is="" appropriate="" and="" necessary="" to="" provide="" for="" capital="" improvements.="" for="" ground="" water="" systems,="" the="" 1994="" proposed="" stage="" 1="" dbpr="" compliance="" schedules="" provided="" for="" only="" one="" half="" of="" the="" risk-risk="" tradeoff="" balance.="" they="" did="" not="" include="" a="" companion="" rule="" development="" and="" compliance="" schedules="" for="" the="" analogous="" microbial="" provisions="" of="" a="" ground="" water="" disinfection="" rule.="" the="" 1996="" sdwa="" amendments="" provide="" an="" outside="" date="" for="" promulgation="" of="" ground="" water="" microbial="" requirements="" of="" ``no="" later="" than''="" may="" 2002,="" but="" leave="" to="" epa="" the="" decision="" of="" whether="" an="" earlier="" promulgation="" is="" more="" appropriate.="" in="" light="" of="" the="" reg-neg="" emphasis="" and="" congressional="" affirmation="" of="" the="" principal="" of="" simultaneous="" compliance="" to="" assure="" no="" risk-risk="" tradeoffs,="" epa="" has="" developed="" a="" ground="" water="" disinfection="" rule="" promulgation="" schedule="" that="" will="" result="" in="" a="" final="" gwdr="" by="" november="" 2000,="" the="" same="" date="" as="" the="" congressional="" deadline="" for="" the="" lteswtr.="" ground="" water="" systems="" would="" be="" required="" to="" comply="" with="" the="" gwdr="" by="" november="" 2003,="" three="" years="" after="" promulgation,="" and="" to="" assure="" simultaneous="" compliance="" with="" dbp="" provisions,="" such="" systems="" would="" be="" required="" to="" comply="" with="" stage="" 1="" dbpr="" requirements="" by="" the="" same="" date.="" again,="" for="" the="" reasons="" outlined="" under="" option="" 2,="" usepa="" believes="" a="" five="" year="" compliance="" period="" for="" ground="" water="" systems="" is="" necessary="" and="" appropriate.="" option="" 4="" assures="" that="" ground="" water="" systems="" will="" be="" required="" to="" comply="" with="" stage="" 1="" dbpr="" provisions="" at="" the="" same="" time="" that="" they="" comply="" with="" the="" microbial="" provisions="" of="" the="" ground="" water="" disinfection="" rule="" (gwdr).="" successful="" implementation="" of="" this="" option="" requires="" that="" epa="" develop="" and="" promulgate="" the="" gwdr="" by="" november="" 2000="" as="" indicated="" above.="" the="" agency="" recognizes="" that="" this="" is="" an="" ambitious="" schedule,="" but="" believes="" it="" is="" necessary="" to="" meet="" the="" twin="" objectives="" of="" simultaneous="" implementation="" and="" consistency="" with="" the="" new="" statutory="" compliance="" provisions="" of="" the="" 1996="" sdwa.="" in="" evaluating="" this="" option,="" the="" agency="" also="" considered="" the="" possibility="" of="" meeting="" these="" twin="" objectives="" in="" a="" somewhat="" different="" fashion="" by="" delaying="" final="" promulgation="" of="" the="" stage="" i="" dbp="" rule="" as="" it="" applies="" ground="" water="" systems="" until="" the="" promulgation="" of="" the="" gwdr.="" this="" alternative="" possibility="" would="" assure="" simultaneous="" compliance="" and="" also="" provide="" a="" ``safety="" net''="" in="" the="" event="" that="" the="" gwdr="" november="" 2000="" promulgation="" schedule="" is="" delayed.="" epa="" is="" concerned,="" however,="" that="" this="" approach="" may="" not="" meet="" or="" be="" consistent="" with="" new="" sdwa="" requirements="" which="" provide="" that="" the="" stage="" i="" dbpr="" be="" promulgated="" by="" november="" 1998.="" the="" agency="" requests="" comment="" on="" this="" issue.="" recommendation="" epa="" has="" evaluated="" each="" of="" the="" considerations="" identified="" in="" options="" 1="" through="" 4.="" on="" balance,="" the="" agency="" believes="" that="" option="" 4="" is="" the="" preferred="" option.="" the="" primary="" reasons="" are="" (1)="" to="" allow="" states="" at="" least="" two="" years="" to="" adopt="" and="" implement="" m-dbp="" rules="" consistent="" with="" new="" two="" year="" time="" frame="" provided="" for="" under="" the="" 1996="" sdwa="" amendments,="" (2)="" to="" match="" the="" compliance="" schedules="" for="" the="" lteswtr="" and="" stage="" 1="" dbpr="" for="" small=""><10,000 served)="" surface="" water="" systems="" to="" allow="" time="" for="" capital="" improvements="" and="" addressing="" risk-risk="" tradeoff="" issues,="" and="" (3)="" to="" assure="" that="" all="" ground="" water="" systems="" simultaneously="" comply="" with="" newly="" applicable="" microbial="" and="" stage="" 1="" dbpr="" requirements="" on="" the="" same="" compliance="" schedule="" provided="" for="" small="" surface="" water="" systems.="" request="" for="" comments="" epa="" requests="" comment="" on="" both="" the="" compliance="" schedule="" options="" discussed="" above="" and="" on="" any="" other="" variations="" or="" combinations="" of="" these="" options.="" epa="" also="" requests="" comment="" on="" its="" preferred="" option="" 4="" and="" on="" the="" underlying="" rationale="" for="" allowing="" a="" five="" year="" compliance="" schedule="" for="" ground="" water="" and="" small="" surface="" water="" systems="" under="" the="" stage="" 1="" dbpr.="" b.="" compliance="" violations="" and="" state="" primacy="" obligations="" a="" public="" water="" system="" that="" fails="" to="" comply="" with="" any="" applicable="" requirement="" of="" the="" sdwa="" (as="" defined="" in="" 1414="" (i))="" is="" subject="" to="" an="" enforcement="" action="" and="" a="" requirement="" for="" public="" notice="" under="" the="" provisions="" of="" section="" 1414.="" applicable="" requirements="" include,="" but="" are="" not="" limited="" to,="" mcls,="" treatment="" techniques,="" monitoring="" and="" reporting.="" these="" regulatory="" requirements="" are="" set="" out="" in="" 40="" cfr="" l41.="" the="" sdwa="" also="" requires="" states="" that="" would="" have="" primary="" enforcement="" responsibility="" for="" the="" drinking="" water="" regulations="" (``primacy'')="" to="" adopt="" regulations="" that="" are="" no="" less="" stringent="" than="" those="" promulgated="" by="" epa.="" states="" must="" also="" adopt="" and="" implement="" adequate="" procedures="" for="" the="" enforcement="" of="" such="" regulations,="" and="" keep="" records="" and="" make="" reports="" with="" respect="" to="" these="" activities="" in="" accordance="" with="" epa="" regulations.="" 5="" u.s.c.="" 1413.="" epa="" may="" promulgate="" regulations="" that="" require="" states="" to="" submit="" reports="" on="" how="" they="" intend="" to="" comply="" with="" certain="" requirements="" (e.g.,="" how="" the="" state="" plans="" to="" schedule="" and="" conduct="" sanitary="" surveys="" required="" by="" the="" ieswtr),="" how="" the="" state="" plans="" to="" make="" certain="" decisions="" or="" approve="" pws-planned="" actions="" (e.g.,="" approve="" significant="" changes="" in="" disinfection="" under="" the="" ieswtr="" or="" approve="" step="" 2="" dbp="" precursor="" removals="" under="" the="" enhanced="" coagulation="" requirements="" of="" the="" stage="" i="" dbpr),="" and="" how="" the="" state="" will="" enforce="" its="" authorities="" (e.g.,="" correct="" deficiencies="" identified="" by="" the="" state="" during="" a="" sanitary="" survey="" within="" a="" specified="" time).="" the="" primacy="" regulations="" are="" set="" out="" in="" 40="" cfr="" 142.="" epa="" drafted="" requirements="" for="" both="" the="" pwss="" (part="" 141)="" and="" the="" primacy="" states="" (part="" 142)="" in="" the="" proposed="" rules.="" epa="" is="" requesting="" comments="" on="" whether="" there="" are="" elements="" of="" the="" advisory="" committee's="" recommendations="" in="" this="" notice="" that="" should="" be="" treated="" as="" applicable="" requirements="" for="" the="" pws="" and="" included="" in="" part="" l41="" as="" enforceable="" requirements.="" similarly,="" epa="" requests="" comments="" on="" whether="" there="" are="" elements="" of="" the="" advisory="" committee's="" recommendations="" in="" this="" notice="" that="" should="" be="" treated="" as="" requirements="" for="" states="" and="" included="" in="" part="" 142="" as="" primacy="" requirements.="" c.="" compliance="" with="" current="" regulations="" epa="" reaffirms="" its="" commitment="" to="" the="" current="" safe="" drinking="" water="" act="" regulations,="" including="" those="" related="" to="" microbial="" pathogen="" control="" and="" disinfection.="" each="" public="" water="" system="" must="" continue="" to="" comply="" with="" the="" current="" rules="" while="" new="" microbial="" and="" disinfectants/disinfection="" byproducts="" rules="" are="" being="" developed.="" m.="" disinfection="" studies="" 1.="" new="" giardia="" inactivation="" studies="" at="" high="" ph="" levels="" the="" surface="" water="" treatment="" rule="" (swtr)="" requires="" plants="" treating="" surface="" [[page="" 59522]]="" water="" to="" meet="" minimum="" inactivation/removal="" requirements="" for="" giardia="" cysts="" and="" viruses.="" under="" the="" swtr,="" the="" concept="" of="" ct="" values="" (disinfectant="" residual="" concentration="" (c="" )="" multiplied="" by="" contact="" time="" (t))="" is="" used="" for="" estimating="" inactivation="" efficiency="" of="" disinfection="" practices="" in="" plants.="" as="" a="" supplement="" to="" the="" rule,="" usepa="" published="" a="" guidance="" manual="" document="" entitled="" ``guidance="" manual="" for="" compliance="" with="" the="" filtration="" and="" disinfection="" requirements="" for="" public="" water="" systems="" using="" surface="" water="" sources''="" (usepa="" 1991a)="" [swtr="" guidance="" manual].="" in="" this="" manual,="" ct="" tables="" (log="" inactivation="" versus="" ct="" values="" under="" different="" environmental="" conditions)="" are="" provided="" to="" utilities="" as="" a="" guidance="" in="" carrying="" out="" the="" disinfection="" requirements.="" the="" swtr="" guidance="" manual="" did="" not="" include="" ct="" values="" at="" ph="" values="" above="" 9="" due="" to="" the="" limited="" research="" results="" available="" at="" the="" time="" of="" rule="" promulgation.="" ph="" values="" above="" 9="" mainly="" exist="" in="" plants="" with="" lime="" softening="" processes.="" an="" approach="" for="" extending="" the="" existing="" ct="" tables="" in="" the="" swtr="" guidance="" manual="" to="" the="" upper="" ph="" boundary="" (ph="" 11.5)="" that="" may="" occur="" in="" some="" plants="" is="" presented="" below.="" with="" this="" approach,="" the="" latest="" available="" data="" reported="" by="" logsdon="" et="" al.="" (1994)="" was="" used="" as="" a="" basis="" for="" ct="" values="" at="" high="" ph="" values="" by="" applying="" a="" linear="" regression="" to="" logsdon's="" experimental="" results="" in="" laboratory="" water="" and="" a="" safety="" factor="" to="" cover="" the="" variability="" in="" natural="" water.="" analysis="" of="" logsdon's="" data:="" logsdon="" et="" al.="" (1994)="" performed="" giardia="" inactivation="" experiments="" with="" free="" chlorine="" in="" both="" laboratory="" and="" natural="" waters="" at="" 5="" deg.c="" and="" at="" ph="" values="" of="" 9.5,="" 10.5,="" and="" 11.5.="" the="" analysis="" of="" mw-s's="" data="" is="" performed="" with="" the="" following="" assumptions:="" 1.="" since="" the="" experimental="" data="" of="" mw-s="" et="" al.="" for="" ct="" values="" vs.="" log="" inactivation="" are="" relatively="" scattered,="" a="" sophisticated="" model="" will="" not="" improve="" the="" result="" of="" simulation.="" rather,="" a="" linear="" regression="" was="" used="" to="" fit="" these="" data="" points,="" by="" assuming="" the="" dilution="" coefficient="" n="1" in="" the="" conventional="" watson's="" law="" (first-order="" kinetics).="" 2.="" data="" points="" for="" inactivation="" greater="" than="" 3-logs="" in="" the="" logsdon="" et="" al.="" report="" are="" not="" included="" in="" the="" linear="" regression="" because="" of="" their="" uncertainty.="" 3.="" data="" points="" for="" natural="" water="" have="" a="" greater="" variability="" than="" those="" for="" laboratory="" water.="" also,="" ct="" tables="" in="" the="" swtr="" guidance="" manual="" were="" developed="" solely="" based="" on="" tests="" using="" laboratory="" water.="" to="" ensure="" consistency,="" therefore,="" data="" points="" for="" natural="" water="" from="" the="" logsdon="" et="" al.="" study="" were="" not="" used.="" however,="" a="" safety="" factor="" was="" applied="" to="" the="" ct="" values="" estimated="" from="" laboratory="" data="" to="" reflect="" the="" variability="" of="" inactivation="" results="" in="" natural="" water.="" 4.="" to="" be="" consistent,="" the="" safety="" factor="" of="" ct="" values="" at="" ph=""> 9 is
assumed to be the same as that for the existing CT values in the SWTR
Guidance Manual at pH 9. To appropriately quantify a safety
factor being applied to obtain those existing CT values in the SWTR
Guidance Manual, the previous data base for pH 9 was
reevaluated and interpreted in the same manner as that for pH > 9
(using a linear regression and a safety factor). Subsequently, the
safety factor was set at a value such that, if multiplied by the CT
values estimated by a linear regression, the resultant CT values would
match the existing CT values in the SWTR Guidance Manual.
5. For determination of a safety factor, data from the following
studies were considered: Jarroll et al. (1981), Rice et al. (1982),
Hibler et al. (1987), and Rubin et al. (1989) [Those data were used as
a basis for developing the existing CT values in the SWTR Guidance
Manual.]. Only the data from Jarroll et al. (1981) were used in the
linear regression because the protocols or conditions in other studies
are not comparable to those used in the study by Logsdon et al. (1994),
as noted below:
(1) The study by Hibler et al. (1987) was based on animal
infectivity tests. Excystation was used in the study by Logsdon et
al. (1994).
(2) The study by Rubin et al. (1989) was conducted only at
15 deg.C while the study by Logsdon et al. (1994) was performed at
5 deg.C.
(3) No data for control excystation was shown in the study by
Rice et al. (1982) and therefore this data was not used in the
regression analysis.
The data from Jarroll et al. (1981) for chlorine concentrations of
4 and 8 mg/L were not used in the regression analysis because the
chlorine residual in the study by Logsdon et al. (1994) was no higher
than 2.1 mg/L.
The Results of Data Analysis: The data from Jarroll et al. (1981)
pertaining to log inactivation versus CT values are plotted in Figures
8--10 for pH values of 6, 7, and 8, respectively. Because Jarroll et
al. found that essentially no inactivation at pH values of 6-8 was
observed in control samples in which no disinfectant was added within
60 minutes (i.e., CT = 0, log inactivation = 0), the intercept of the
linear regression line was zero.
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The regression results with the values of the Watson coefficient k
are shown in each figure. Based on these results, CT values for a
designated log inactivation at the three different pH values are
estimated and shown in Table 6. By trials, it is found that if a safety
factor of 1.5 is applied to those estimated CT values, the resulting CT
values approximate the values in the SWTR Guidance Manual for chlorine
concentration 2 mg/L: at pH 6, the safety-factored CT
values are slightly higher than those in the SWTR Guidance Manual; at
pH 7, the safety-factored CT values are about in the middle of the
range of CT values in the SWTR Guidance Manual; at pH 8, the safety-
factored CT values are in the low range of CT values in the SWTR
Guidance Manual. Therefore, a safety factor of 1.5 appears appropriate
for the development of CT tables at higher pHs.
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The Logsdon data for Giardia inactivation with chlorine are shown
in Figures 11-13 for pH values of 9.5, 10.5, and 11.5, respectively.
Since Logsdon et al. (1994) also observed that little or no
inactivation was caused by a high pH itself (i.e., non-disinfected lime
softened water) in at least 6 hours, the intercept of the linear
regression line should be zero. Based on the determinant k values
indicated in each Figure, CT values required for inactivation in the
range of 0.5-3 log at pH values of 9.5-11.5 and temperature of 5 deg.C
are estimated and tabulated in Table 7. To evaluate the adequacy of the
safety factor value (1.5), the line of log inactivation versus the
safety-factored CT values is also shown in each of Figures 11-13. It
can be seen from Figures 11 and 12 that most data points for natural
water are above the safety-factored line, and few points are near the
line, indicating the safety factor of 1.5 is appropriate for the
establishment of CT tables for pH > 9.
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Table 7.--Estimated CT Values for pH=9.5-11.5 at C 2 mg/L
and at 5 deg.C--Based on the Logsdon's Study for Laboratory Water
------------------------------------------------------------------------
Estimated Estimated
pH Log CT mg-min/ CT x
inactivation L 1.5 S.F.
------------------------------------------------------------------------
pH=9.5.............................. 0.5 21 32
1 42 63
1.5 62 93
2 83 124
2.5 104 156
3 125 188
pH=10.5............................. 0.5 70 105
1 141 212
1.5 211 316
2 282 423
2.5 352 528
3 422 633
pH=11.5............................. 0.5 128 192
1 256 384
1.5 385 578
2 513 770
2.5 641 962
3 769 1154
------------------------------------------------------------------------
By comparing the data in Table 6 and 10, it is seen that estimated
CT values at pH 9.5 are consistently lower than those at pH 8 in the
SWTR Guidance Manual. To maintain the consistency of an increasing
trend of CT values with an increasing pH and be conservative for
compliance purposes, the mathematical model described in the SWTR
Guidance Manual (equation 15 in Appendix F) by Clark and Regli (1993)
is used to extend the existing CT tables in the SWTR Guidance Manual to
pH=9.5, e.g., CT=60 mg/L for 0.5 log inactivation with 1 mg/L of
chlorine at 5 deg.C. As proposed in the SWTR Guidance Manual, the
equation can be directly applied to estimate CT values for 0.5 and
5 deg.C, and a twofold decrease in CT values for every 10 deg.C
increase in temperature can be assumed when it is higher than 5 deg.C.
Consequently, the CT
[[Page 59530]]
values for Giardia inactivation with free chlorine at pH 9.5 are
computed and shown in Table 8.
The same temperature correction factor above is used to estimate CT
values for pH values of 10.5 and 11.5 at temperature from 5 to
25 deg.C, and 1.5 of temperature factor is applied to convert CT values
at 5 deg.C to those at 0.5 deg.C. Subsequently, the safety-factored CT
values for Giardia inactivation with free chlorine were estimated and
summarized in Tables 11 and 13 for pH values of 10.5 and 11.5,
respectively. It should be mentioned that although the level of
chlorine residual (the C value) may affect CT values shown in Tables 12
and 13, it is recommended that those values are only applicable to a C
value up to 3 mg/L, at least until more research data become available.
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In summary, the CT table for Giardia inactivation with free
chlorine at pH 9.5 was developed by using the same approach in the SWTR
Guidance Manual for the existing CT tables at lower pH values. For the
development of CT tables at pH values of 10.5 and 11.5, the data
reported by Logsdon et al. (1994) was used with a linear regression
multiplied by a safety factor of 1.5. The new CT values are shown in
Tables 11, 12, and 13 for pH values of 9.5, 10.5, and 11.5,
respectively. USEPA solicits comment on the approach taken and whether
the CT values shown in Tables 11, 12 and 13 are appropriate for
revising existing guidance for estimating inactivation efficiencies for
chlorine at pHs above 9. USEPA also solicits comment on other
approaches for developing criteria by which systems could estimate
inactivation efficiencies at pHs above 9.
2. Effectiveness of Different Disinfectants on Cryptosporidium
When the ESWTR was proposed in 1994, USEPA recognized that chlorine
disinfectants were relatively ineffective in inactivating
Cryptosporidium, but was not certain if alternative disinfectants might
be more effective than chlorine. No public comment addressed this issue
directly. Studies since the proposal have confirmed the ineffectiveness
of chlorine species, such as free chlorine and monochloramine, for the
practical inactivation of Cryptosporidium. However, new data suggest
that sequential disinfection with free chlorine followed by
monochloramine can achieve a greater degree of Cryptosporidium
inactivation than by chlorine alone. Moreover, ozone and chlorine
dioxide have been found to be much more effective than chlorine.
Sequential disinfection such as ozone or chlorine dioxide followed by
one of the chlorine species appears more powerful than either
disinfectant alone in inactivating Cryptosporidium. The following data
detail the inactivation of Cryptosporidium by individual disinfectants,
as well as by sequential disinfectants.
The purpose of presenting this data in this section is to provide
the public opportunity to comment on whether there is (a) sufficient
information available for generating CT tables to estimate log
inactivation of Cryptosporidium, comparable to what was done for
Giardia under the SWTR, and (b) sufficient data to conclude that
chlorination, at levels commonly practiced by utilities, is virtually
ineffective for inactivating Cryptosporidium. Both of these issues
relate to USEPA's rationale for using Giardia as the key target
organism for defining the disinfection benchmark (see Section D).
Table 11a summarizes the data on disinfection of Cryptosporidium
with
[[Page 59534]]
chlorine species and ultraviolet radiation (UV). The results from
studies with free chlorine indicate that some inactivation of C. parvum
could be achieved at relatively high doses of chlorine (i.e., >1,000
mg/L of chlorine bleach and 80 mg/L of free chlorine) (Korich et al.,
1990a; Ransome et al., 1993) and a high CT value (7,200 mg-min/L)
(Korich et al., 1990a; Lykins et al., 1992). However, this common water
disinfectant has been conclusively shown to be ineffective for
inactivation of C. parvum oocysts at practical plant doses (<6 mg="">2/L) or CT values (Korich et al., 1990a; Ransome et al.,
1993; Finch et al., 1997). The same is essentially true for
monochloramine (Lykins et al., 1992; Finch et al., 1997) and the
oxidant of permanganate (Finch et al., 1997). Therefore, it is unlikely
that significant inactivation of Cryptosporidium will occur in water
treatment plants with the single addition of these disinfectants at
currently used levels.
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As indicated in Table 11a, the literature data on Cryptosporidium
inactivation with UV appear controversial because of different
experimental protocols used by different investigators. Finch et al.
(1997) found that UV was ineffective in inactivating C. parvum
suspended in a batch reactor. However, significant inactivation was
observed when the oocysts were captured in 2cm filters and exposed to a
preset UV irradiation dose (Campbell et al., 1995; Clancy et al.,
1997). More data are needed to evaluate the practical application of UV
for inactivation of Cryptosporidium oocysts. Also, of interest are
possible synergistic effects with UV application followed by residual
disinfectants.
Table 11b summarizes the findings of inactivation of
Cryptosporidium with ozone. The data obtained from bench-scale tests
with oxidant-demand-free laboratory water indicate that for CT values
between 1.2-23.0 mg-min/L, the range of inactivation was 0.5 to 5 log
at temperatures of 5 to 25 deg.C and at pH values of 7 to 8 (Peeters
et al., 1989; Korich et al., 1990a,b; Parker et al., 1993; Ransome et
al., 1993; Finch et al., 1994 & 1997). The variability demonstrated in
these results is influenced by the differences in test procedures used
by different researchers, i.e., the different measures of
Cryptosporidium inactivation (infectivity, excystation, etc.) and the
different methods of CT calculations (initial ozone dose, average ozone
concentration, and ozone residual).
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Therefore, caution should be used when comparing the results from
one study to another. For instance, a CT value of 10 mg-min/L for 0.5-
log inactivation was obtained from the study conducted by Parker et al.
(1993), who used vital dyes to evaluate the viability of
Cryptosporidium. This result is incomparable to the data shown in Table
11b. Subsequently, Korich et al. (1993) found that vital stains are of
questionable value for determining oocyst viability.
In another example, in a series of experiments at pH 7 and at
temperatures of 5-22 deg.C, Finch et al. (1997) found a 45-92%
reduction in ozone concentration at initial residuals of 0.6-2.2 mg/L
and contact times of 5-15 minutes. Parker et al. (1993) reported that
the Cryptosporidium inactivation level was greater when the ozone
concentration was maintained at a constant level (i.e., through a batch
mode reactor), compared to when the same initial ozone dose was allowed
to decay during the same contact time. Both Finch et al. (1994) and
Parker et al. (1993) found that an increase in temperature caused a
higher inactivation at the same ozone residual and the same contact
time. It appears that an increase of 15 deg.C decreases by half the CT
values needed for a 2-log inactivation.
Owens et al. (1994) observed that C. muris is slightly more
resistant to ozone than C. parvum, and proposed that C. muris be used
as a surrogate model for C. parvum. However, the data that support this
hypothesis are very limited.
Two pilot-scale studies with natural waters have been performed
(Danial et al., 1993; Miltner et al., 1997). The CT values of ozone
required to achieve 2- and 3-logs inactivation of Cryptosporidium were
6.0 mg-min/L (pH 8, 24 deg.C) (Miltner et al., 1997) and 10-15 mg-min/
L (pH 7, 15 deg.C) (Danial et al., 1993). It appears that higher CT
values are required in natural water for inactivation of
Cryptosporidium than in laboratory water; this may be attributed to the
existing oxidant demands in natural water or other factors. Danial et
al. (1993) indicated that the ozone residual for a given dose rapidly
decomposed as the pH was increased from 7 to 9 during lime addition.
This finding implies that if ozonation is practiced in lime-softening
water plants, it will be necessary to adjust the pH downstream.
When inactivation of Cryptosporidium oocysts is compared with that
of Giardia cysts with similar test protocols, C. parvum is
approximately 10 times more resistant to ozone than G. lamblia in
laboratory water (Finch et al., 1994) and G. muris in natural water
(Owens et al., 1994; Miltner et al., 1997). These findings imply that
the use of ozone cannot be expected to significantly inactivate
Cryptosporidium at the concentration and contact times employed in
inactivating Giardia in water treatment practices.
Table 11c summarizes the findings of Cryptosporidium inactivation
with chlorine dioxide. For CT values between 23-213 mg-min/L, the range
of inactivation is 0.5-3.2 log or higher at temperatures of 10-25
deg.C and at pH values of 7-8 in laboratory water (Peeters et al.,
1989; Korich et al., 1990b; Ransome et al., 1993; Finch et al., 1995 &
1997). Similar to ozone, chlorine dioxide is also unstable in the
water. In 0.05 M phosphate buffer water at pH 8 and 22 deg.C, Finch et
al. (1997) found that a 49-99% reduction in chlorine dioxide
concentrations occurs after 15-120 minutes at initial residuals of
0.36-3.3 mg/L. LeChevallier et al. (1997b) recently performed a pilot-
scale study in a natural water by evaluating viability of oocysts with
both an in-vitro excystation assay and a tissue culture infectivity.
While the difference in results with the two methods was not shown, the
study reported that a CT value of 40 mg-min/L results in 1-log
inactivation of oocysts at pH 8.0 and 20 deg.C, and a 0.5-log
inactivation at pH 6.0. The study also revealed that a temperature
reduction from 20 to 10 deg.C decreases the effectiveness of chlorine
dioxide by 40%.
The existing data show chlorine dioxide as an effective
disinfectant for Cryptosporidium inactivation. However, CT values
required for Cryptosporidium inactivation appear much higher than those
for same log inactivation of Giardia under comparable water conditions
(Lisle and Rose, 1995). Since the 1994 D/DBP proposed rule has set the
maximum contaminant levels for chlorine dioxide and chlorite (by-
product of chlorine dioxide), at 0.8 mg/L and 1 mg/L, respectively, the
use of chlorine dioxide may be limited for the inactivation of
Cryptosporidium.
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Table 12 summarizes the results from Finch et al. (1997). Finch et
al. found that sequential disinfection of C. parvum oocysts by
different disinfectants is more effective than that indicated by the
effectiveness of each disinfectant from independent studies, i.e., the
effect is synergistic. According to their current report, greater than
2.9-log inactivation of oocysts can be achieved when C. parvum is
exposed to 0.75 mg/L initial ozone residual for 3.7 minutes and then
2.0 mg/L free chlorine residual for 265 minutes (pH 6). Based on the
additive effects of ozone and free chlorine alone under similar
conditions, a 2.0-logs inactivation is expected. Similarly, the
inactivation by monochloramine following ozonation is increased by 1.5
log-units when compared with either ozone or monochloramine alone.
Additional 1.2-log inactivation due to the synergism of chlorine
dioxide and free chlorine has also been obtained at pH 8. Furthermore,
sequential exposure of C. parvum oocysts to free chlorine followed by a
monochloramine (pH 8.0) reduces infectivity by 0.6 log. Since the
expected inactivation by either chlorine species at pH 8 is virtually
zero, there is a synergism between free chlorine and monochloramine. It
should be noted that combinations of chlorine species with other
disinfectants may stimulate the formation of chlorate (Siddiqui et al.,
1996) or other toxic disinfectant byproducts. Also, the synergistic
effect with sequential disinfectants has only been observed in bench-
scale studies in a single laboratory. Nevertheless, such findings
suggest new strategies for the effective inactivation of
Cryptosporidium. For a practical application, further investigations
are being conducted at a wider range of water quality conditions (pH,
temperature, and disinfectant demand) (USEPA, 1995b).
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Analytical Method--Four analytical methods are currently being used
to evaluate inactivation of Cryptosporidium oocysts: in vitro
excystation, vital dyes (DAPI/PI staining), animal infectivity, and
tissue culture infectivity. It has been shown that excystation and
DAPI/PI staining consistently underestimate inactivation when compared
with animal infectivity, which is more expensive (Finch et al., 1994;
Black et al., 1996). The use of different animal models also leads to
inconsistent results for Cryptosporidium infectivity. Although the
tissue culture technique may provide a convenient, low-cost alternative
to animal infectivity, only limited data exist with this method
(LeChevallier et al., 1997b).
Cryptosporidium Inactivation Map--In conjunction with development
of the long-term ESWTR, USEPA is developing a graph of CT values versus
log inactivation under various water quality conditions. The Agency is
also exploring other means that utilities can use to estimate
Cryptosporidium inactivation with different single or sequential
disinfectants. Additional data, especially under natural water/field
conditions, is necessary to develop this graph. Finch et al. (1994)
attempted to establish CT tables for Cryptosporidium inactivation with
ozone by analyzing numerous sets of experimental data by using both the
Chick-Watson model and the Hom model. It was found that the
inactivation kinetics of C. parvum by ozone deviated from the simple
first-order Chick-Watson model and was better described by a nonlinear
Hom model. A further analysis, however, hasn't been performed on a
broader data basis to evaluate such a finding. Moreover, a much better
understanding of Cryptosporidium inactivation with sequential
disinfectants is needed.
3. New Virus Inactivation Studies
One of the treatment options that USEPA proposed as part of the
ESWTR was to include a 4-logs minimal inactivation requirement for
viruses, in addition to any physical removal of viruses that might be
achieved. USEPA intends to consider this option when additional data
become available. However, significant data are available regarding
disinfection conditions necessary to achieve different inactivation
levels of viruses. The availability of such data is discussed below.
USEPA's guidance manual to the SWTR (USEPA, 1991a), assumes that CT
values for chlorine necessary to achieve a 0.5-log inactivation of
Giardia cysts will result in greater than a 4-log inactivation of
viruses. This assumption is based on the comparison between the effects
of free chlorine on Giardia lamblia and hepatitis A virus (HAV). In the
proposed ESWTR, USEPA noted that some viruses are more resistant to
chlorine than is HAV, and the use of disinfectants other than free
chlorine to achieve 0.5-log inactivation of Giardia may not yield a 4-
log inactivation of viruses. Achieving adequate inactivation of viruses
may be of greater concern when disinfectants other than chlorine (e.g.,
chlorine dioxide and ozone) are used to inactivate Cryptosporidium
oocysts.
CT tables in the SWTR for estimating viral inactivation efficiency
with chlorine dioxide and ozone were based on laboratory studies using
HAV and poliovirus 1, respectively. Very few studies have since been
conducted to investigate viral inactivation with chlorine dioxide.
Huang et al. (1997) evaluated the disinfection effects of chlorine
dioxide on six viruses, including poliovirus type 1, coxsackievirus
type B3, echovirus 11, adenovirus type 7, herpes simplex
virus 1, and mumps virus. All viruses were completely inactivated at
CT=90 mg-min/L (3 mg/L of initial dose and 30 minutes of contact time)
at pH values of 3, 5, and 7, but not 9. Complete inactivation of all
six viruses was also found at CT=30 mg-min/L (1 mg/L of initial dose
and 30 minutes of contact time) at pH 7.0. At 7.0 mg/L of initial dose,
greater than 10 minutes of contact time were required for complete
inactivation at the same pH.
More studies have been performed to evaluate viral inactivation
efficiencies by ozone than by chlorine dioxide. The results from these
studies are summarized in Table 13.
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In general, the tested viruses, including HAV, MS2 coliphage,
poliovirus 1 (PV1), poliovirus 3 (PV3), and T2 phage, are relatively
sensitive to ozone, and more than 4-logs inactivation of these viruses
can be achieved with less than 2 mg/L of ozone and 5 minutes of contact
time in a wide range of pH values and temperatures (Herbold et al.,
1989; Kaneko, 1989; Vaughn et al., 1990; Finch et al., 1992; Hall and
Sobsey, 1993; Miltner et al., 1997). Finch et al. (1992) reported that
MS2 coliphage was extremely sensitive to ozone in both laboratory water
and natural water, and that complete viral inactivation could occur
during the process of satisfying ozone demand in natural water. In
paired experiments, they also found that there was significantly less
inactivation of PV3 than MS2 coliphage under the same ozonation
conditions. In contrast, Hall and Sobsey (1993) demonstrated that MS2
coliphage was at least as resistant to ozone as HAV in a pH range of 6-
10, suggesting that MS2 coliphage might be a good model for predicting
HAV inactivation by ozone. In a continuous-flow system with a constant
flow of ozone and viral suspensions, Herbold et al. (1993) found that
HAV required approximately three times the ozone that PV1 required for
the same inactivation. In a similar system, Botzenhart et al. (1993)
showed that MS2 coliphage was more resistant to ozone than PhiX 174
coliphage.
Some researchers have pointed out that viral disinfection with
ozone is difficult to evaluate, not only due to the relatively short
inactivation times, but also because the concentration of ozone
significantly decreases during the contact time. Finch et al. (1992)
found ozone dose and the interaction between ozone dose and dissolved
organic carbon (DOC) were the most important factors affecting ozone
inactivation of MS2 coliphage in surface waters. Inactivation of MS2
coliphage was significantly reduced when the natural DOC in the water
increased during spring runoff, presumably because the ozone
concentration was rapidly depleted by the DOC. This effect, however,
was not observed when an ozone residual of 0.1 mg/L at the end of 30
seconds was detected, resulting in greater than 4-logs inactivation of
MS2 coliphage under all water quality conditions.
Finch et al. (1992) found that the effects of temperature and
turbidity on inactivation rates were indistinguishable from
experimental error. This contrasts with other studies that reported
that viral inactivation with ozone was more efficient at lower
temperatures (Botzenhart et al., 1993; Herbold et al., 1993), and the
presence of kaolin particles at 1 mg/L or higher resulted in a greater
level of ozone residual required for the same level of viral
inactivation (Kaneko, 1989). Vaughn et al. (1990) observed that the pH-
related effects on ozonation of viruses was not significant in a pH
range of 6-8. Kaneko (1989) reported that the presence of ammonium
decreased the ozone concentration and thus decreased the inactivation
efficiency of ozone.
Kaneko (1989) also revealed that ozonation of viruses could be
divided into three phases: an initial large reduction of viruses; a
subsequent logarithmic reduction of viruses; and finally, a slow
reduction in response to decreasing ozone concentrations. Thus, it is
not surprising that the viral inactivation rate beginning 5 minutes
after adding the disinfectant was greater with chlorine than with
ozone, even though the inactivation rates within 5 minutes of the
addition of ozone were 10 to 1,000 higher than the initial rates of
inactivation with chlorine (Kaneko and Igarashi, 1983; Kaneko, 1989).
Finch et al. (1992) have concluded that, when comparing the ozone
inactivation data for MS2 coliphage, PV3, and Giardia muris, the
conditions for inactivating G. muris cysts are the most rigorous and it
is likely that enteric viruses will be inactivated by greater than 4
logs when Giardia is inactivated by 3 logs. Such a comparison is also
needed for chlorine dioxide. Although the tested enteric viruses appear
to be more susceptible to ozone than Giardia, no data are yet available
on the effectiveness of ozone in inactivating Norwalk virus and other
pathogenic human viruses, especially when they are clumped and adsorbed
to organic matter as they usually are in natural water. The varying
results on viral inactivation with ozone suggest that ozone
inactivation studies need to measure and report ozone concentrations
over time.
III. Economic Analysis of the M-DBP Advisory Committee
Recommendations
A. Overview of RIA for Proposed Rule
The Regulatory Impact Analysis (RIA) for the proposed IESWTR (59 FR
38832, July 29, 1994), estimated national capital and annualized costs
(amortized capital and annual operating costs) for surface water
systems serving at least 10,000 people at $3.6 billion and $391 million
respectively. These costs were based on the assumption that systems
would also be required to provide enough treatment to achieve less than
a 10-4 risk level from giardiasis while meeting the Stage 1
DBPR. In estimating these costs, it was assumed that additional Giardia
reduction beyond the requirements of the SWTR to achieve the
10-4 risk level would be achieved solely by using chlorine
as the disinfectant and providing additional contact time by increasing
the disinfectant contact basin size.
The Regulatory Impact Analysis for the Interim Enhanced Surface
Water Treatment Rule (USEPA, 1994d) predicted that ESWTR compliance
would result in no more than a few hundred infections caused by
waterborne Giardia per year per 100 million people. This is hundreds of
thousands of cases fewer than predicted in the absence of an ESWTR.
USEPA estimated that the benefit per Giardia infection avoided would be
$3000 per case. Using this estimate, the 400,000 to 500,000 Giardia
infections per year that could be avoided would have an economic value
of $1.2 to $1.5 billion per year. This suggests that the benefit
nationwide of avoiding Giardia infections is as much as three or four
times greater than the estimated $391 million national annual cost of
providing additional contact time.
Table 14 shows this $391 million estimated cost as described in the
proposal (using 1992 $s and a discount rate of 10 percent). The table
also converts this cost to 1997$s (with a 10 percent discount rate) to
provide for comparison with costs based on provisions included in this
notice.
For a more detailed discussion of the cost and benefit analysis of
the 1994 proposal refer to The Regulatory Impact Analysis for the
Interim Enhanced Surface Water Treatment Rule (USEPA, 1994d).
B. What's Changed Since the Proposed Rule
The cost estimates in the proposed rule reflect cost estimates for
one of several regulatory alternatives included in the proposal. At the
time of proposal USEPA assumed that additional data would be collected
under the ICR to more accurately estimate costs and benefits of the
Giardia based rule option as well as alternative regulatory options.
National source water occurrence data for Giardia and Cryptosporidium
are being collected as part of the ICR to help this effort. Due to the
delays discussed earlier in this Notice and the new expedited rule
deadlines, ICR data will not be available for the IESWTR impact
analysis. From February 1997, however, the Agency has worked with
stakeholders to identify additional data available since 1994 to be
used in developing components of the
[[Page 59545]]
expedited rules. USEPA established the Microbial and Disinfectants/
Disinfection Byproducts Advisory Committee to collect, share and
analyze new information and data, as well as to build consensus on the
regulatory implications of this new information. The Committee met five
times from March to July, 1997 to discuss issues related to the IESWTR
and Stage I D/DBPR.
USEPA has also evaluated comments received on the proposal in its
consideration of elements to be included in a regulatory option
independent of ICR source water occurrence data. These comments
suggested (1) sufficient degrees of effectiveness of current treatment,
including filtration, in preventing waterborne transmission of
Cryptosporidium and (2) a revised approach focussing on optimizing
treatment processes. In response to these comments, new information
received and the Advisory Committee's recommendations, USEPA has
developed the Economic Analysis described in summary below. Details of
the analysis used to derive the costs and benefits described below are
available in the draft document Economic Analysis of M/DBP Advisory
Committee Recommendations for the Interim Enhanced Surface Water
Treatment Rule (USEPA, 1997a). The economic analyses are based on the
Committee's recommendations to USEPA on issues including turbidity
control, removal of Cryptosporidium, disinfection benchmarking and
sanitary surveys.
C. Summary of Cost Analysis
1. Total National Costs
USEPA is considering several approaches, based on the
recommendations of the Advisory Committee. The two most substantial
approaches, from the perspective of costs and benefits, govern
turbidity performance and turbidity monitoring. The Microbial and
Disinfectants/Disinfection Byproducts Committee made a number of
recommendations that are indicated in this Notice for comment,
including new turbidity provisions with associated monitoring
requirements, disinfection benchmarking practices to help ensure there
are no significant increases in microbial risk while systems comply
with the Stage 1 DBPR and a sanitary survey provision of relatively
minimal costs. USEPA estimates that the national capital and annualized
costs (amortized capital and annual operating costs) of these
provisions (based on a 10 percent interest rate) would be $730 million
and $312 million, respectively [Table 14] (USEPA, 1997a). These figures
include costs associated with improved treatment, turbidity monitoring,
a disinfection benchmark and sanitary surveys. This represents a
reduction of over $3.4 billion (in 1997 $s) from the capital costs
estimated for the proposed rule. This is accounted for primarily by the
recommendations for changes in the level of disinfection required and
restoration of disinfection credit prior to precursor removal. This
would result in fewer systems needing to install additional
disinfectant contact basins, relative to the costs in the 1994
proposal.
A discount rate of 10 percent was used to calculate the unit costs
for the national cost model. This discount rate provides both a link to
the 1994 IESWTR cost analyses and is a reasonable estimation of the
cost to utilities to finance capital purchases assumed to be necessary
due to the proposal.
In order to demonstrate the sensitivity of the national cost model
to different discount rates, the national costs at 10 percent are
compared to national costs calculated using a 7% discount rate. This
rate represents the standard social discount rate preferred by the
Office of Management and Budget for benefit-cost analyses of government
programs and regulations. Tables of unit cost estimates at the 7
percent rate are included in the appendix to the draft Economic
Analysis and displayed for comparative purposes (USEPA, 1997a). Costs
presented in the Economic Analysis are expressed in June 1997 constant
dollars.
The water flow rates that were used in calculating the costs of the
1994 proposal (in 1992 $s and 1997 $s) were also used in calculating
the national costs of the recommended provisions discussed in this
Notice. Additional analyses gauged the sensitivity of the cost model to
a different input value for maximum flow rates for the largest system
category (systems serving >1 million people). With this adjusted flow
rate (using a 10 percent discount rate) total annualized national costs
would be $314 million, compared to $312 million based on flow rates
used in the 1994 proposal.
USEPA requests comment on how the new data have been used and any
additional data that would improve the assessment of costs and
benefits.
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2. Household Costs
Household costs are a way to represent water system treatment costs
as a costs to the system customer. Figure 14 displays results of the
household cost analyses for a 0.3 NTU, 1 maximum CFE NTU turbidity
treatment approach discussed in this Notice. As can be seen from the
graph, a small percentage of the systems might, using this methodology,
incur a maximum cost per household of approximately $110 per year. The
highest household costs are incurred in households served by small
systems that need to implement all of the activities to comply.
It must be borne in mind that the upper bound of the graph displays
an extrapolated curve, and does not represent actual data points. The
assumptions and structure of this analysis, in describing the curve,
tend to overestimate the highest costs. To find itself on the upper
bound of the curve, a system would have to implement all, or almost
all, of the treatment activities. These systems, conversely, might seek
less costly alternatives, such as connecting into a larger regional
water system. In the judgment of the Advisory Committee's Technical
Work Group, this extreme situation and the resulting high values may
occur only for a small number of households.
Based on this analysis, over 97 percent of the households are
estimated to incur annual costs of less than $20 per household per year
and over 50 percent are estimated to incur costs of less than $2 per
household per year.
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D. Cost of Turbidity Performance Criteria and Associated Monitoring
1. System Level Impact Analysis
The TWG developed a list of treatment activities that systems would
be expected to employ in order to implement Advisory Committee
recommendations. These activities were grouped into 10 categories based
on general process descriptions as follows; chemical addition,
coagulant improvements, rapid mixing, flocculation improvements,
settling improvements, filtration improvements, hydraulic improvements,
administration culture improvements, laboratory modifications and
process control testing modifications. Descriptions of how systems were
expected to evaluate these activities are described in the draft
document Technologies and Costs for the Interim Enhanced Surface Water
Treatment Rule (USEPA, 1997b).
2. National Impact Analyses
a. Decision Tree. The decision tree is a table of treatment
activities that taken either singly or in combination will help
utilities evaluate what is potentially involved in meeting the
turbidity limits recommended by the Advisory Committee, i.e., the
requirement that utilities serving more than 10,000 people be required
to achieve a 95 percentile turbidity limit of 0.3 NTU and at no time
exceed a turbidity value of 1 NTU (Appendix A, USEPA, 1997a).
Percentages in a decision tree represent the projected percentage of
public water systems using that activity to meet the turbidity limits
recommended by the Advisory Committee. These percentages were factors
in the national cost model
[[Page 59548]]
and generally represent the percentage of systems needing to modify
treatment to meet the limits.
Further description of the compliance decision tree and methodology
are included in the draft Economic Analysis of M/DBP Advisory Committee
Recommendations for the Interim Enhanced Surface Water Treatment Rule
(Economic Analysis) (USEPA, 1997a).
b. Utility Costs. Turbidity Treatment. The number of systems, the
associated total capital costs, and the associated total annualized
costs were estimated for seven system size categories. Total annual
costs were calculated for each possible treatment activity and for each
system size category. Unit costs were converted to annualized cost
totals (in thousands of dollars) using the methodology described in the
draft Economic Analysis.
As indicated in Table 14, the estimate of national annualized
turbidity treatment costs are $203 million based on the Advisory
Committee's recommended 0.3 NTU 95th percentile CFE standard while
meeting a 1 NTU maximum combined filter effluent level (calculated with
a 10% interest rate in 1997$s).
Turbidity Monitoring. A generalized turbidity monitoring model was
developed to provide a framework for estimating costs associated with
individual filter monitoring. The model assumes turbidimeters for each
filter and an on-line Supervisory Control And Data Acquisition (SCADA)
system. Filter readings would be taken at least once every 15 minutes
and tabulated. The model assumes that once each work shift (8 hours)
the turbidity data would be converted to a reviewable form, and would
then be reviewed by a system manager. In cases where the monitoring
recorded exceedances as described below, a report would be made to the
State and, if warranted, an individual filter review or system
assessment might occur. Annual utility monitoring costs are estimated
at $96 million as shown in Table 14 above.
Under the approach recommended by the Advisory Committee, exception
reporting to the State is warranted if:
--An individual filter has a turbidity level greater than 1.0 NTU for 2
consecutive measurements 15 minutes apart.
--An individual filter has a turbidity level greater than 0.5 NTU at
the end of the first 4 hours of filter operation for 2 consecutive
measurements 15 minutes apart.
--If a plant reports exceedances of 1.0 NTU at one filter for 3
consecutive months, an individual filter assessment (IFA) is required
to be performed by the utility.
--If a plant records exceedances of 2.0 NTU at one filter in 2
consecutive months, a comprehensive performance evaluation (CPE) is
required and must be performed by a third party.
c. State Costs. Annual Review Costs. Under the recommended
provisions, it would be the State's responsibility to review system
data to ensure that all systems in the State are in compliance with the
provisions. State activities include compliance tracking, review of
Statewide utility data, record keeping, and compliance determinations.
Annual State costs for review (nationwide) are estimated to be $5.3
million (USEPA, 1997a).
Implementation and Start-Up Costs Related to Turbidity Monitoring.
One-time State implementation activities include the adoption of the
rule and State regulation development. As shown in Table 14, the rule
would collectively cost States a total of $407,000 to implement
turbidity monitoring provisions.
Exception Costs (Exception Reports, IFAs and CPEs). Under the
approach recommended by the Advisory Committee, a monthly exception
report would be filed by each utility at which a plant exceeds
individual filter effluent (IFE) turbidities of either 1.0 NTU for 2
consecutive measurements 15 minutes apart, or 0.5 NTU at the end of the
first 4 hours of a filter run.
In addition to the monthly exception report of individual filter
effluent exceedances, additional steps are triggered when exceedances
persist. If an individual filter has turbidity levels greater than 1.0
NTU based on 2 consecutive measurements fifteen minutes apart at any
time in each of 3 consecutive months, the system conducts a self
assessment of the filter utilizing as guidance relevant portions of
guidance issued by the Environmental Protection Agency for
Comprehensive Performance Evaluation (CPE). If an individual filter has
turbidity levels greater than 2.0 NTU based on 2 consecutive
measurements fifteen minutes apart at any time in each of two
consecutive months, the system will arrange for the conduct of a CPE by
the State or a third party approved by the State.
The following assumptions were made by the Technical Working Group
of the Advisory Committee regarding the percentage of systems per year
that would trigger an interaction with the State based on the
recommended provisions.
--10 percent of systems per year are assumed to file monthly reports to
the State based on individual filter effluent provisions
--2 percent of systems per year are assumed to trigger Individual
Filter Assessment (IFA) provisions
--1 percent of systems per year are assumed to trigger Comprehensive
Performance Evaluation (CPE) provisions.
Based on these assumptions, approximately 28 IFAs and 14 CPEs will
be conducted each year at an estimated cost of $5,000 and $25,000 each,
respectively. States are expected, therefore, to incur annual costs
(nationally) of $64,000 to review the exception reports, $138,000 and
$345,300 in annual costs for IFAs and CPEs, respectively. The combined
total annual State cost for these items is $572,000 (Table 14, above).
E. Disinfection Benchmark
1. Decision Tree
The Advisory Committee recommended that a utility prepare a
disinfection profile if they:
--measure TTHM levels of at least 80 percent of the MCL (0.064 mg/l) as
an annual average for the most recent 12-month period for which
compliance data are available.
--measure HAA% level of at least 80 percent of the MCL (0.048 mg/l) as
an annual average for the most recent 12-month compliance period for
which compliance data are available.
HAA and TTHM figures from the 1996 Water Industry Data Base (WIDB)
were used to estimate the percentage of systems that would be required
to prepare a disinfection profile.
2. Utility Costs
Utility costs associated with profiling were divided into four
activity areas; cost per system, cost per plant using paper data (i.e.,
for those plants that currently use paper to document their plant
profile data), cost per plant using mainframe data, and cost per plant
using PC data. Plants with paper data were assumed to represent half of
the number of plants needing profiling, while plants with mainframe
data and plants with PC data each represent 25 percent of all plants.
The TWG assumed that all plants currently collect this data in either
an electronic or paper format, and, therefore, would not incur
additional data collection expenses due to microbial profiling. Data
reporting costs per plant that are associated with microbial profiling
include; data entry and spreadsheet development, data manipulation and
analysis, and data
[[Page 59549]]
review. Costs per system include those to; read and understand the
rule, mobilization and planning, generation of reports to State and for
in-house review, and meet and review profile with the State. The
national costs associated with microbial profiling for utilities was
estimated at $2.7 million [Table 14].
3. State Costs
States will review profiles as part of its sanitary survey process.
Utilities required to develop a disinfection profile that subsequently
decide to make a significant change in disinfection practice must
consult with the state prior to making such a change. Table 14 details
the total national State costs of profiling (one-time) at $3.1 million.
F. Sanitary Surveys
States are expected to conduct sanitary surveys on a rotating
basis, in general no less frequently than once every 3 years for
community water systems (CWSs) and no less frequently than every 5
years for noncommunity water systems (NCWSs). For this analysis, 80
percent of Systems are assumed to have already conducted a sanitary
survey. The remaining 20 percent of systems are considered to require
new surveys in order to comply with the requirements in the IESWTR. The
total national cost estimate for sanitary surveys, as shown in Table
14, is estimated at $6.7 million.
G. Summary of Benefits Analysis
The economic benefits of the provisions recommended by the Advisory
Committee derive from the increased level of protection to public
health. The primary goal of these provisions is to improve public
health by increasing the level of protection from exposure to
Cryptosporidium and other pathogens in drinking water supplies through
improvements in filtration at water systems. In this case, benefits
will accrue due to the decreased likelihood of endemic incidences of
cryptosporidiosis, giardiasis and other waterborne disease, and the
avoidance of resulting health costs. In addition to reducing the
endemic disease, the provisions are expected to reduce the likelihood
of the occurrence of Cryptosporidium outbreaks and their associated
economic costs, by providing a larger margin of safety against such
outbreaks for some systems.
The benefits analysis quantitatively examines health damages
avoided based on the provisions recommended by the Advisory Committee.
The assessment also discusses, but does not quantify, other economic
benefits that may result from the provisions, including reduced risk of
outbreaks, avoided costs of averting behavior such as boiling water.
The assessment of net benefits is always somewhat problematic due
to the relative ease of quantifying compliance treatment costs versus
the difficulty of assigning monetary values to the avoidance of health
damages and other benefits arising from a regulation. The challenge of
assessing net benefits for the recommended provisions is compounded by
the fact that there are large areas of scientific uncertainty regarding
the exposure to and the risk assessment for Cryptosporidium. Areas
where important sources of uncertainty enter the benefits assessment
include the following.
Occurrence of Cryptosporidium oocysts in source waters.
Occurrence of Cryptosporidium oocysts in finished waters.
Reduction of Cryptosporidium oocysts due to treatment,
including filtration and disinfection.
Viability of Cryptosporidium oocysts after treatment.
Infectivity of Cryptosporidium.
Incidence of infections and associated symptomatic
response (including impact of under reporting).
Characterization of the risk.
Willingness to pay to reduce risk and avoid costs.
The cumulative impact of these uncertainties on the outcome of the
exposure and risk assessment is impossible to measure. The benefit
analysis attempts to take into account some of these uncertainties by
estimating benefits under two different current treatment assumptions
and three improved removal assumptions. The benefit analysis also used
Monte Carlo simulations to derive a distribution of estimates, rather
than a single point estimate.
The following two assumptions were made about the performance of
current treatment in removing or inactivating oocysts to estimate
finished water Cryptosporidium concentrations. The standard assumption
is that current treatment results in a mean physical removal and
inactivation of oocysts of 2.5 logs and a standard deviation
0.63 logs). Because the finished water concentrations of
oocysts represent the baseline against which improved removal from the
recommended provisions is compared, variations in the log removal
assumption could have considerable impact on the risk assessment. To
evaluate the impact of the removal assumptions on the baseline and
resulting improvements, an alternative mean log removal/inactivation
assumption of 3.0 logs (and a standard deviation 0.63 logs)
was also used to calculate finished water concentrations of
Cryptosporidium.
USEPA made three assumptions about the improved log removal of
oocysts that would result from the turbidity provisions recommended by
the Advisory Committee. These were based on studies of treatment
removal efficiencies discussed earlier in this Notice (Table 1:
Cryptosporidium and Giardia lamblia removal efficiencies by rapid
granular filtration). A range of 2-6 logs removal of Cryptosporidium
oocysts were observed in these studies. USEPA assumed that a certain
number of plants would show low, mid or high improved removal,
depending upon factors such as water matrix conditions, filtered water
turbidity effluent levels, and coagulant treatment conditions.
The finished water Cryptosporidium distributions that would result
from additional log removal with the turbidity provisions were derived
assuming that additional log removal was dependent on current removal,
as described above, i.e., that sites currently achieving the highest
filtered water turbidity performance levels would show the largest
improvements or high improved removal assumption (e.g., plants now
failing to meet a 0.4 NTU limit would show greater removal improvements
than plants now meeting a 0.3 NTU limit). Table 15 contains the
assumptions used to generate the new treatment distribution.
Table 15.--Improved Removal Assumptions
------------------------------------------------------------------------
Additional log removal with committee recommendations
-------------------------------------------------------------------------
Low Mid High
------------------------------------------------------------------------
Plants now meeting 0.2 NTU
limit......................... None None None
Plants operating between 0.2-
0.3 NTU....................... 0.15 0.25 0.3
Plants now meeting 0.4 NTU
limit......................... 0.35 0.5 0.6
[[Page 59550]]
Plants now failing to meet 0.4
NTU limit..................... 0.5 0.75 0.9
------------------------------------------------------------------------
The TWG working group assumed that for plants to achieve a 0.3 NTU
95th percentile standard they would operate their plants to achieve a
0.2 NTU limit. Therefore, systems meeting a 95th percentile limit of
0.2 NTU were assumed to make no further treatment changes to meet a 0.3
NTU standard, and therefore show no incremental increase in log
removal.
Given the uncertainties described above, assumptions were made in
developing the risk characterization. In summary, USEPA assumed:
--an exponential dose/response function for estimating infection rates
(Haas et al., 1996)
--2 liters per person daily water consumption with a log normal
distribution (Haas and Rose, 1995)
--a national surface water distribution of oocysts based on Monte Carlo
analysis of data collected by LeChevallier and Norton (USEPA, 1996a)
--A uniform distribution of percentage of oocysts that would be
infectious with a mean value of 10 percent
--An estimated 0.39 mean ratio (triangular distribution) of people that
are infected to people that become ill (Haas, et al., 1996).
--The cost of an avoided case of cryptosporidiosis was estimated to be
approximately $1800 per case. This was extrapolated from the estimate
of $3,000 for giardiasis used in the RIA for the proposal, and based on
the relatively shorter average length of illness.
Risk characterization uses these assumptions to calculate the
number of illnesses avoided in Table 16. Using this number of illnesses
avoided, the cost of illnesses avoided is calculated under each current
log treatment assumption (i.e., 2.5 and 3.0 logs) for each of the
improved removal assumptions. Table 16 summarizes the mean expected
value of potential benefits expected to accrue to the recommended
provisions under the six different scenarios, as well as the range.
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IV. National Technology Transfer and Advancement Act
Under section 12(d) of the National Technology Transfer and
Advancement Act (``NTTAA''), the Agency is required to use voluntary
consensus standards in its regulatory activities unless to do so would
be inconsistent with applicable law or otherwise impractical. Voluntary
consensus standards are technical standards (e.g., materials
specifications, test methods, sampling procedures, business practices,
etc.) that are developed or adopted by voluntary consensus standards
bodies. Where available and potentially applicable voluntary consensus
standards are not used by EPA, the Act requires the Agency to provide
Congress, through the Office of Management and Budget, an explanation
of the reasons for not using such standards.
The Agency does not believe that this Notice addresses any
technical standards subject to the NTTAA. A commenter who disagrees
with this conclusion should indicate how the Notice is subject to the
Act and identify any potentially applicable voluntary consensus
standards.
References
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Appendix A--U.S. Environmental Protection Agency, Microbial/
Disinfection by-Products (M/DBP), Federal Advisory Committee
Agreement in Principle
1.0 Introduction
Pursuant to requirements under the Safe Drinking Water Act
(SDWA), the Environmental Protection Agency (EPA) is developing
interrelated regulations to control microbial pathogens and
disinfectants/disinfection byproducts (D/DBPs) in drinking water.
These rules are collectively known as the microbial/disinfection
byproducts (M/DBP) rules.
The regulations are intended to address complex risk trade-offs
between the two different types of contaminants. In keeping with the
agreement reached during the 1992-93 negotiated rulemaking on these
matters, EPA issued a Notice of Proposed Rulemaking for Disinfection
By-Products Stage I on July 29, 1994. EPA also issued a Notice of
Proposed Rulemaking for an Interim Enhanced Surface Water Treatment
Rule (IESWTR) on July 29, 1994. Finally, in May 1996, EPA
promulgated a final Information Collection Rule (ICR), to obtain
data on source water quality, byproduct formation and drinking water
treatment plant design and operations.
As part of recent amendments to the SDWA, Congress has
established deadlines for all the M/DBP rules, beginning with a
November 1998 deadline for promulgation of both the IESWTR and the
Stage I D/DBP Rule. To meet this new deadline, EPA initiated an
expedited schedule for development of these two rules. Building on
the 1994 proposals, EPA intends to issue a Notice of Data
Availability (NODA) in November 1997 for public comment. EPA also
decided to establish a committee under the Federal Advisory
Committee Act (FACA) for development of the rules.
The M/DBP Advisory Committee is made up of organizational
members (parties) named by EPA (see Attachment A). The immediate
task of the Committee has been to discuss, evaluate and provide
advice on data, analysis and approaches to be included in the NODA
to be published in November 1997. This Committee met four times from
March through June 1997, with the initial objective to reach
consensus, where possible, on the elements to be contained in the D/
DBP Stage I and IESWTR NODA. Where consensus was not reached, the
Committee sought to develop options and/or to clarify key issues and
areas of agreement and disagreement. This document is the
Committee's statement on the points of agreement reached.
2.0 Agreement in Principle
The Microbial and Disinfection By-Products Federal Advisory
Committee considered the technical and policy issues involved in
developing a DBP Stage I rule and an IESWTR under the Safe Drinking
Water Act and recommends that the Environmental Protection Agency
base the applicable sections of its anticipated M/DBP Notice of Data
Availability (NODA) on the elements of agreement described below.
This agreement in principle represents the consensus of the
parties on the best conceptual principles that the Committee was
able to generate within the allocated time and resources available.
The USEPA, a party to the negotiations, agrees that:
1. The person signing this agreement is authorized to commit
this party to its terms.
2. EPA agrees to hold a meeting in July 1997 following
circulation of a second draft of the NODA to obtain comments from
the parties and the public on the extent to which the applicable
sections of the draft NODA are consistent with the agreements below.
3. Each party and individual signatory that submits comments on
the NODA agrees to support those components of the NODA that reflect
the agreements set forth below. Each party and individual signatory
reserves the right to comment, as individuals or on behalf of the
organization he or she represents, on any other aspect of the Notice
of Data Availability.
4. EPA will consider all relevant comments submitted concerning
the Notice(s) of Proposed Rulemaking and in response to such
comments will make such modifications in the proposed rule(s) and
preamble(s) as EPA determines are appropriate when issuing a final
rule.
5. Recognizing that under the Appointments Clause of the
Constitution governmental authority may be exercised only by
officers of the United States and recognizing that it is EPA's
responsibility to issue final rules, EPA intends to issue final
rules that are based on the provisions of the Safe Drinking Water
Act, pertinent facts, and comments received from the public.
6. Each party agrees not to take any action to inhibit the
adoption of final rule(s) to the extent it and corresponding
preamble(s) have the same substance and effect as the elements of
this agreement in principle.
[[Page 59556]]
2.1 MCLs
MCLs should remain at the levels proposed: 0.080 mg/l for TTHMs,
0.060 mg/l for HAA5, and 0.010 mg/l for bromate.
2.2 Enhanced Coagulation
The proposed enhanced coagulation provisions should be revised
as follows:
a. The top row of the TOC removal table (3x3 matrix) should be
modified for systems that practice enhanced coagulation by lowering
the TOC removal percentages by 5% across the top row, while leaving
the other rows the same.
b. SUVA (specific UV absorbance) should be used for determining
whether systems would be required to use enhanced coagulation. The
use of a raw water SUVA < 2.0="" liter/mg-m="" as="" a="" criterion="" for="" not="" requiring="" a="" system="" to="" practice="" enhanced="" coagulation="" should="" be="" added="" to="" those="" proposed="" in="" sec.="" 141.135(a)(1)(i)-(iv).="" c.="" for="" a="" system="" required="" to="" practice="" enhanced="" coagulation="" or="" enhanced="" softening,="" the="" use="" of="" a="" finished="" water="" suva="">< 2.0="" liter/mg-="" m="" should="" be="" added="" as="" a="" step="" 2="" procedure.="" such="" a="" criterion="" would="" be="" in="" addition="" to="" the="" proposed="" step="" 2="" procedure,="" not="" in="" lieu="" of="" it.="" d.="" the="" proposed="" toc="" removals="" for="" softening="" systems="" should="" be="" modified="" by="" lowering="" the="" value="" for="" toc="" removal="" in="" the="" matrix="" at="" alkalinity="">120 mg/l and TOC between 2-4 mg/l by 5% (which would
make it equal to the value for non-softening systems) and leaving
the remaining values as proposed.
e. If a system is required to practice enhanced softening, lime
softening plants would not be required to perform lime soda
softening or to lower alkalinity below 40-60 mg/l as part of any
Step 2 procedure.
f. There is no need to separately address softening systems in
the 3x3 matrix or the Step 1 regulatory language, which was
identical to enhanced coagulation regulatory language in the
proposed D/DBPR. The revised matrix should appear as follows:
------------------------------------------------------------------------
------------------------------------------------------------------------
(2) Alkalinity (mg/l)
TOC (mg/l)............................. 0-< 60="">< 120="">8..................................... 50 40 30
------------------------------------------------------------------------
2.3 Microbial Benchmarking/Profiling
A microbial benchmark to provide a methodology and process by
which a PWS and the State, working together, assure that there will
be no significant reduction in microbial protection as the result of
modifying disinfection practices in order to meet MCLs for TTHM and
HAA5 should be established as follows:
A. Applicability. The following PWSs to which the IESWTR applies
must prepare a disinfection profile:
(1) PWSs with measured TTHM levels of at least 80% of the MCL
(0.064 mg/l) as an annual average for the most recent 12 month
compliance period for which compliance data are available prior to
November 1998 (or some other period designated by the State),
(2) PWSs with measured HAA5 levels of at least 80% of the MCL
(0.048 mg/l) as an annual average for the most recent 12 month
period for which data are available (or some other period designated
by the State)--In connection with HAA5 monitoring, the following
provisions apply:
(a) PWSs that have collected HAA5 data under the Information
Collection Rule must use those data to determine the HAA5 level,
unless the State determines that there is a more representative
annual data set.
(b) For those PWSs that do not have four quarters of HAA5 data
90 days following the IESWTR promulgation date, HAA5 monitoring must
be conducted for four quarters.
B. Disinfection profile. A disinfection profile consists of a
compilation of daily Giardia lamblia log inactivations (or virus
inactivations under conditions to be specified), computed over the
period of a year, based on daily measurements of operational data
(disinfectant residual concentration(s), contact time(s),
temperature(s), and where necessary, pH(s)). The PWS will then
determine the lowest average month (critical period) for each 12
month period and average critical periods to create a ``benchmark''
reflecting the lower bound of a PWS's current disinfection practice.
Those PWSs that have all necessary data to determine profiles, using
operational data collected prior to promulgation of the IESWTR, may
use up to three years of operational data in developing those
profiles. Those PWSs that do not have three years of operational
data to develop profiles must conduct the necessary monitoring to
develop the profile for one year beginning no later than 15 months
after promulgation, and use up to two years of existing operational
data to develop profiles.
C. State review. The State will review disinfection profiles as
part of its sanitary survey. Those PWSs required to develop a
disinfection profile that subsequently decide to make a significant
change in disinfection practice (i.e., move point of disinfection,
change the type of disinfectant, change the disinfection process, or
any other change designated as significant by the State) must
consult with the State prior to implementing such a change.
Supporting materials for such consultation must include a
description of the proposed change, the disinfection profile, and an
analysis of how the proposed change will affect the current
disinfection.
D. Guidance. EPA, in consultation with interested stakeholders,
will develop detailed guidance for States and PWSs on how to develop
and evaluate disinfection profiles, identify and evaluate
significant changes in disinfection practices, and guidance on
moving the point of disinfection from prior to the point of
coagulant addition to after the point of coagulant addition.
2.4 Disinfection Credit
Consistent with the existing provisions of the 1989 Surface
Water Treatment Rule, credit for compliance with applicable
disinfection requirements should continue to be allowed for
disinfection applied at any point prior to the first customer.
EPA will develop guidance on the use and costs of oxidants that
control water quality problems (e.g., zebra mussels, Asiatic clams,
iron, manganese, algae) and whose use will reduce or eliminate the
formation of DBPs of public health concern.
2.5 Turbidity
Turbidity Performance Requirements. For all surface water
systems that use conventional treatment or direct filtration, serve
more than 10,000 people, and are required to filter: (a) the
turbidity level of a system's combined filtered water at each plant
must be less than or equal to 0.3 NTU in at least 95 percent of the
measurements taken each month and, (b) the turbidity level of a
system's combined filtered water at each plant must at no time
exceed 1 NTU. For both the maximum and the 95th percentile
requirements. compliance shall be determined based on measurements
of the combined filter effluent at four-hour intervals.
Individual Filter Requirements. All surface water systems that
use rapid granular filtration, serve more than 10,000 people, and
are required to filter shall conduct continuous monitoring of
turbidity for each individual filter and shall provide an exceptions
report to the State on a monthly basis. Exceptions reporting shall
include the following: (1) any individual filter with a turbidity
level greater than 1.0 NTU based on 2 consecutive measurements
fifteen minutes apart; and (2) any individual filter with a
turbidity level greater than 0.5 NTU at the end of the first 4 hours
of filter operation based on 2 consecutive measurements fifteen
minutes apart. A filter profile will be produced if no obvious
reason for the abnormal filter performance can be identified.
If an individual filter has turbidity levels greater than 1.0
NTU based on 2 consecutive measurements fifteen minutes apart at any
time in each of 3 consecutive months, the system shall conduct a
self-assessment of the filter utilizing as guidance relevant
portions of guidance issued by the Environmental Protection Agency
for Comprehensive Performance Evaluation (CPE). If an individual
filter has turbidity levels greater than 2.0 NTU based on 2
consecutive measurements fifteen minutes apart at any time in each
of two consecutive months, the system will arrange for the conduct
of a CPE by the State or a third party approved by the State.
State Authority. States must have rules or other authority to
require systems to conduct a Composite Correction Program (CCP) and
to assure that systems implement any follow-up recommendations that
result as part of the CCP.
2.6 Cryptosporidium MCLG
EPA should establish an MCLG to protect public health. The
Agency should describe existing and ongoing research and areas of
scientific uncertainty on the question of which species of
Cryptosporidium represents a concern for public health (e.g. parvum,
muris, serpententious) and request further comment on whether to
establish an MCLG on the genus or species level.
In the event the Agency establishes an MCLG on the genus level,
EPA should make clear that the objective of this MCLG is to protect
public health and explain the nature of scientific uncertainty on
the issue of
[[Page 59557]]
taxonomy and cross reactivity between strains. The Agency should
indicate that the scope of MCLG may change as scientific data on
specific strains of particular concern to human health become
available.
2.7 Removal of Cryptosporidium
All surface water systems that serve more than l 0,000 people
and are required to filter must achieve at least a 2 log removal of
Cryptosporidium. Systems which use rapid granular filtration (direct
filtration or conventional filtration treatment--as currently
defined in the SWTR), and meet the turbidity requirements described
in Section 2.5 are assumed to achieve at least a 2 log removal of
Cryptosporidium. Systems which use slow sand filtration and
diatomaceous earth filtration and meet existing turbidity
performance requirements (less than 1 NTU for the 95th percentile or
alternative criteria as approved by the State) are assumed to
achieve at least a 2 log removal of Cryptosporidium.
Systems may demonstrate that they achieve higher levels of
physical removal.
2.8 Multiple Barrier Concept
EPA should issue a risk-based proposal of the Final Enhanced
Surface Water Treatment Rule for Cryptosporidium embodying the
multiple barrier approach (e.g. source water protection, physical
removal, inactivation, etc.), including, where risks suggest
appropriate, inactivation requirements. In establishing the Final
Enhanced Surface Water Treatment Rule, the following issues will be
evaluated:
Data and research needs and limitations (e.g.
occurrence, treatment, viability, active disease surveillance,
etc.);
Technology and methods capabilities and limitations;
Removal and inactivation effectiveness;
Risk tradeoffs including risks of significant shifts in
disinfection practices;
Cost considerations consistent with the SDWA;
Reliability and redundancy of systems;
Consistency with the requirements of the Act.
2.9 Sanitary Surveys
Sanitary surveys operate as an important preventive tool to
identify water system deficiencies that could pose a risk to public
health. EPA and ASDWA have issued a joint guidance dated 12/21/95 on
the key components of an effective sanitary survey. The following
provisions concerning sanitary surveys should be included.
I. Definition
(A) A sanitary survey is an onsite review of the water source
(identifying sources of contamination using results of source water
assessments where available), facilities, equipment, operation,
maintenance, and monitoring compliance of a public water system to
evaluate the adequacy of the system, its sources and operations and
the distribution of safe drinking water.
(B) Components of a sanitary survey may be completed as part of
a staged or phased state review process within the established
frequency interval set forth below.
(C) A sanitary survey must address each of the eight elements
outlined in the December 1995 EPA/STATE Guidance on Sanitary
Surveys.
II. Frequency
(A) Conduct sanitary surveys for all surface water systems
(including groundwater under the influence) no less frequently than
every three years for community systems except as provided below and
no less frequently than every five years for noncommunity systems.
--May ``grandfather''sanitary surveys conducted after December 1995, if
they address the eight sanitary survey components outlined above.
(B) For community systems determined by the State to have
outstanding performance based on prior sanitary surveys, successive
sanitary surveys may be conducted no less than every five years.
III. Follow Up
(A) Systems must respond to deficiencies outlined in a sanitary
survey report within at least 45 days, indicating how and on what
schedule the system will address significant deficiencies noted in
the survey.
(B) States must have the appropriate rules or other authority to
assure that facilities take the steps necessary to address
significant deficiencies identified in the survey report that are
within the control of the PWS and its governing body.
Agreed to by:
----------------------------------------------------------------------
Name, Organization
----------------------------------------------------------------------
Date
Signed By:
Peter L. Cook, National Association of Water Companies
Michael A. Dimitriou, International Ozone Association
Cynthia C. Dougherty, US Environmental Protection Agency
Mary J.R. Gilchrist, American Public Health Association
Jeffrey K. Griffiths, National Association of People with AIDS
Barker Hamill, Association of State Drinking Water Administrators
Robert H. Harris, Environmental Defense Fund
Edward G. Means III, American Water Works Association
Rosemary Menard, Large Unfiltered Systems
Erik D. Olson, Natural Resources Defense Council
Brian L. Ramaley, Association of Metropolitan Water Agencies
Charles R. Reading Jr., Water and Wastewater Equipment Manufacturers
Association
Suzanne Rude, National Association of Regulatory Utility
Commissioners
Ralph Runge, Chlorine Chemistry Council
Coretta Simmons, National Association of State Utility Consumer
Advocates
Bruce Tobey, National League of Cities
Chris J. Wiant, National Association of City and County Health
Officials; National Environmental Health Association
[FR Doc. 97-28747 Filed 10-31-97; 8:45 am]
BILLING CODE 6560-50-P
